William R. Lindsay was Lead Consultant Clinical Psychologist, Head of Research and Clinical Director in Scotland for the Danshell Group. He was previously Head of Psychology (Learning Disabilities) for NHS Tayside and Consultant Clinical Psychologist at The State Hospital, the high secure hospital serving Scotland and Northern Ireland. Bill Lindsay was Professor of Learning Disabilities and Forensic Psychology at the University of Abertay, Dundee and he held honorary professorships at Bangor University in Wales, Deakin University in Melbourne, Australia, the University of West of Scotland, and Northumbria University in England. He was involved in obtaining over £1 million in research funding and he published over 300 research articles and book chapters. He also wrote and coedited several landmark books in the intellectual disabilities and forensic fields and he edited and coedited numerous special issues of academic journals. Bill Lindsay gave hundreds of keynote addresses, conference presentations, and workshops on cognitive behavioral therapy for, and the assessment and treatment of offending behavior by people with intellectual and developmental disabilities. He received numerous awards from national and international organizations, such as the British Psychological Society (BPS) and the National Association for Dually Diagnosed (NADD) in the United States, in recognition of his contributions to the science and practice of psychology with people who had intellectual disabilities. Bill Lindsay died suddenly in March 2017 soon after the manuscript for this handbook was completed.

John L. Taylor is Professor of Clinical Psychology at Northumbria University, Newcastle upon Tyne and Consultant Clinical Psychologist and Associate Director for Psychological Services with Northumberland, Tyne & Wear NHS Foundation Trust, UK. He is a chartered clinical and forensic psychologist and an Approved Clinician under the Mental Health Act 1983. He qualified as a clinical psychologist from Edinburgh University and has worked mainly in intellectual disability and forensic services in a range of settings in the UK (community and high, medium, and low secure services). He is Chair of the British Psychological Society’s (BPS) Mental Health Act Advisory Group and a past President of the British Association for Behavioural and Cognitive Psychotherapies (BABCP). Dr. Taylor has published over 120 research papers, books, book chapters and articles. He has also presented papers and invited addresses at more than 60 national and international conferences related to his clinical research interests in the assessment and treatment of mental health and in the emotional problems and offending behavior associated with intellectual disabilities. He received an Award for Outstanding Contribution to Applied Practice in 2017.

Regi T. Alexander is Consultant Psychiatrist at St. Johns House, Norfolk, and Research Lead Consultant for Adults with Developmental Disorders at Leicestershire Partnership NHS Trust, UK. Dr. Alexander is the Editor of the Oxford Textbook of Psychiatry of Intellectual Disability and was a member of the UK National Institute of Healthcare and Excellence (NICE) Guidelines Development Group on mental health problems in people with learning disabilities.

Salma Ali is a Liaison & Diversion Practitioner specializing in working with people with intellectual disability. She is also a Forensic Psychologist in Training and has worked with young people and adults with mental health, substance misuse, and intellectual disabilities for over 15 years. Currently she works within Liaison & Diversion services at Central & North‐West London Foundation Trust, and has been integral in the development of the RAPID screening tool, and with the implementation of screening and assessment pathway for offenders with intellectual disability. She has spoken at a number of conferences and had a number of publications within this area, and continues to find ways of ensuring that the needs of offenders with intellectual disabilities are appropriately identified and addressed.

Danyal Ansari is a Clinical Associate in Applied Psychology at The Universities of Dundee and Stirling, and is employed with NHS Greater Glasgow & Clyde. His work focuses on providing cognitive behavioral therapy for individuals experiencing common mental health problems. He has previously worked with individuals who have intellectual and developmental disability and autism where he provided clinical and forensic input to the service.

Nigel Beail is Consultant Clinical Psychologist and Professional Lead for Psychological Services with South West Yorkshire Partnership NHS Foundation Trust, UK. He is also Professor and Clinical Lecturer at the Clinical Psychology Unit, Department of Psychology at the University of Sheffield. He has published extensively on practice‐based research from his clinical work.

Susan E. Breckon is a Clinical Psychologist with Northumberland, Tyne & Wear NHS Foundation Trust, UK. She works clinically in the rehabilitation of patients with intellectual disabilities and complex developmental disorders who are detained under the Mental Health Act 1983 because of offending behavior and mental health problems. Her work focuses on a formulation‐based approach to risk management and care planning at the point of discharge from secure services.

Warren Brookbanks is Professor of Criminal Law and Justice Studies and Director of the Centre for Non‐Adversarial Justice at the Auckland University of Technology Law School. He has coauthored or edited books on forensic psychiatry and law, unfitness to stand trial, criminal justice, and therapeutic jurisprudence. In recent years has undertaken research for the New Zealand, English and Scottish Law Commissions, the New Zealand Ministry of Health, and the former Mental Health Commission. He was a founding Trustee of the Odyssey House Trust (NZ), a former President of the Australia and New Zealand Association of Psychiatry, Psychology and Law (ANZAPPL), and is currently chair of the Oakley Mental Health Foundation Trust Board.

Verity Chester has a background in forensic psychology and is a Research Associate in the Department of Psychiatry at St Johns House, Norfolk, UK and a PhD Candidate at the University of East Anglia where she is researching the offending behavior of people with intellectual or developmental disabilities. She also coordinates the Clinical Research Group in Forensic and Intellectual and Developmental Disabilities.

Isabel C. H. Clare is a Consultant Clinical & Forensic Psychologist working in health services research with the NIHR CLAHRC (Collaboration for Leadership in Applied Health Research & Care) East of England at Cambridgeshire and Peterborough NHS Foundation Trust, and in the Department of Psychiatry, University of Cambridge, UK. She has been a clinical academic throughout her career, with both her clinical work and her research focusing particularly on the assessment, treatment, and support of people with intellectual disabilities and/or other neurodisabilities whose behavior has, or could, bring them into contact with the criminal justice system. With colleagues, she has carried out many grant‐funded research studies in these and related areas and has published extensively.

Leam A. Craig is a Consultant Forensic Clinical Psychologist and Partner at Forensic Psychology Practice Ltd. He is Professor (Hon) of Forensic Psychology at the University of Birmingham and visiting Professor of Forensic Clinical Psychology at Birmingham City University, UK. He is a Chartered and Registered [Forensic and Clinical] Psychologist. Dr. Craig is a Fellow of the British Psychological Society and of the Academy of Social Sciences and recipient of the Senior Academic Award by the Division of Forensic Psychology. His practice includes services to forensic adult mental health and learning disability hospitals, prison, and probation services and he currently works as a consultant to the National Probation Service on the Offenders with Personality Disorder Pathway. He chairs the British Psychological Society Expert Witness Advisory Group. Dr. Craig has over 90 publications including 10 books and he is a series editor for the What Works in Offender Rehabilitation book series for Wiley Blackwell.

P. Ann Dirks‐Linhorst is Professor of Criminal Justice Studies at Southern Illinois University Edwardsville, in the US. She previously served as Forensic Director for the Missouri Department of Mental Health. Her research interests include the intersection of the mental health and criminal justice systems.

Fergus Douds is a Consultant Psychiatrist in intellectual disability and a general adult psychiatrist. His special interest is in forensic intellectual disability issues. Dr. Douds is employed at The State Hospital, Carstairs in Scotland, UK with responsibility for high secure intellectual disability services for Scotland and Northern Ireland and is lead clinician for the Scottish Forensic Network (Intellectual Disability).

Ian Freckelton is a Queen’s Counsel in full‐time practice as a barrister throughout Australia. He is Professorial Fellow of Law and Psychiatry at the University of Melbourne, and Adjunct Professor of Forensic Medicine at Monash University, La Trobe University, Queensland University of Technology, and Auckland University of Technology. He is the Editor of the Journal of Law and Medicine and the Editor‐in‐Chief of Psychiatry, Psychology and Law. He is a Life Member and former President of the Australian and New Zealand Association of Psychiatry, Psychology and Law (ANZAPPL). He has authored over 40 books and more than 500 peer reviewed articles.

Scott Galloway is a Consultant Chartered Clinical and Practitioner Psychologist and was the Clinical Director and Lead Psychologist for the Central & North‐West London Foundation Trust Learning Disabilities Services for 10 years. Dr. Galloway has worked for 24 years in the field of intellectual disabilities, working in and managing both community and specialist inpatient assessment and treatment services for people with mild to moderate intellectual disabilities, autism spectrum disorders, mental illness, personality disorders, and challenging or violent behavior, including those with a forensic history. He has recently worked on the development of the RAPID screening tool as part of the establishment of the screening and assessment service for offenders with intellectual disability.

Beverley Garrigan is a PhD student at the Department of Clinical Psychology, University of East Anglia, UK. Her PhD focuses on moral decision‐making in typically developing adolescents and those with acquired brain injuries. She has a BSc in Psychology from the University of Manchester and an MSc in Applied Forensic Psychology from the University of York.

Gina Gómez de la Cuesta is a Specialist Clinical Psychologist in Cambridge, UK. She did her PhD at the Autism Research Centre at the University of Cambridge, UK under the supervision of Professor Simon Baron Cohen and Dr. Ayla Humphrey. She has set up Bricks for Autism, running training courses for professionals in how to use LEGO^® in social skills groups for children on the autism spectrum. Currently she is involved with the NIHR‐funded I‐SOCIALISE trial evaluating the effectiveness of LEGO^® based therapy in schools with Professor Barry Wright, York University.

Nicola S. Gray is a Chartered Clinical and Forensic Psychologist. Currently she is Professor of Psychology at Swansea University, UK and Director of the Welsh Applied Risk Research Network (WARRN). She received her PhD from the Institute of Psychiatry, University of London and has worked within the NHS and Cardiff University before her present posts. Dr. Gray’s research interests are in risk assessment and safety planning, psychopathy, personality disorder, sexual offending, and neuropsychology. She regularly trains professionals on structured professional judgment for the assessment of future risk and management and other schemes for risk management. She has published widely in the areas of risk assessment, psychopathy, implicit cognitions, and schizophrenia.

Dorothy Griffiths is a Professor in the Child and Youth Studies Department and the Centre for Applied Disability Studies and Co‐Director of the International Dual Diagnosis Certificate Programme at Brock University in St. Catharines, Canada. She has published and written extensively on the topics related to persons with intellectual disabilities who demonstrate challenging sexual behavior and issues regarding human rights.

Richard P. Hastings is Professor of Education and Psychology at the University of Warwick in the UK. He is a researcher with interests in a range of topics in the field of intellectual disabilities and autism. Dr. Hasting’s research with colleagues focuses in particular on psychological problems prevalent amongst children and adults with disabilities, especially challenging behavior, mental health problems, and forensic needs. His research team and collaborators also study the demands of caring for and supporting children and adults with disabilities in the family home, and in education, health, and social care settings.

Fabian Haut is a Consultant Psychiatrist trained in general adult psychiatry and the psychiatry of intellectual disability. He has worked with people with intellectual disability in Tayside, Scotland, UK for more than 20 years. His clinical interests include dual diagnosis and offending behavior. Dr. Haut’s responsibility includes forensic learning disability community services, learning disability intensive support services. Previously he was the Responsible Medical Officer to low secure forensic and forensic assessment intellectual disability units.

Susan Hayes is a forensic psychologist and Professor Emeritus at Sydney University Medical School, Officer of the Order of Australia (AO), Fellow of International Society for the Scientific Study of Intellectual and Developmental Disability, and member of Australian Psychological Society’s College of Forensic Psychology. She is recognized internationally for expertise with people with intellectual disability in the justice system, including the areas of criminal justice (offenders and victims of crime), family court, capacity for medical consent, guardianship, and child protection. Dr. Hayes has authored over 120 publications and 100 conference presentations, and received 30 research grants; she teaches both postgraduate and undergraduate courses.

David Hingsburger is the Director of Clinical and Educational Services at Vita Community Living Services, Toronto, Canada. He has authored and coauthored books, chapters, and articles on issues arising in providing services to people with intellectual disabilities who have engaged in sexual offending behavior, on self‐advocacy and assertions skills, and on providing positive behavioral support. He lectures internationally.

Jordan Hoath has been working in the intellectual disability field in Ontario, Canada for over 10 years in a variety of roles, specifically providing assessment and treatment to individuals with problematic sexual behaviors.

Stephanie Ioannou is a behavior therapist and Board Certified Behaviour Analyst and works with individuals with intellectual disabilities and high risk behavior in Toronto, Canada.

Peter E. Langdon is a Senior Lecturer in Clinical Psychology and Disability at the Tizard Centre, University of Kent, UK as well as an Honorary Consultant Clinical and Forensic Psychologist, working within Hertfordshire Partnership University NHS Foundation Trust, in Norfolk. He is a Research Fellow with the National Institute for Health Research and is Coeditor of the Journal of Applied Research in Intellectual Disabilities. He has worked in forensic mental health care services for over 15 years and has a specific interest in developing clinical interventions for offenders with intellectual and other developmental disabilities.

Donald M. Linhorst is Professor of Social Work and Director of the School of Social Work at Saint Louis University in St. Louis, Missouri, USA. His research interests include empowerment of vulnerable populations, as well as criminal justice programs that address, mental illness, substance abuse, or intellectual and developmental disorders.

Rachael Lofthouse is a Clinical Psychologist with the Forensic Outreach Service, Lancashire Care NHS Trust, in the UK. She completed her PhD at Bangor University focusing on risk factors for offending behavior in adults with intellectual disabilities. She continued research in this area as part of her clinical psychology training at the University of Liverpool. She has worked mainly in intellectual disability and forensic services and continues to have a research interest in these areas.

Amanda M. Michie is a Consultant Clinical Psychologist and the Professional Lead Psychologist for Learning Disability Services in the City of Edinburgh, Mid, East and West Lothian. She has specialist expertise in the field of forensic intellectual disabilities and provides a clinical service to community and inpatient forensic settings across the Lothian region. Dr. Michie works closely with criminal justice system staff providing training, consultancy, and clinical input. She is also an established researcher, publishing regularly, particularly on the assessment and treatment of offenders with intellectual disabilities.

Catrin Morrissey has worked in the forensic intellectual disability field for 30 years. As Lead Psychologist in the National High Secure Learning Disability Service (at Rampton Hospital, UK) she led a team who developed psychological care pathways for high risk males in secure hospital care. She has researched and published widely on the subject of personality disorder in intellectual disability.

Glynis H. Murphy is Professor of Clinical Psychology & Disability at the Tizard Centre, University of Kent, UK. She is a chartered clinical and forensic psychologist, and Fellow of the British Psychological Society. She was President of the International Association of the Scientific Study of Intellectual Disabilities (IASSID) between 2008 and 2012. She was coeditor of Journal of Applied Research in Intellectual Disabilities until the end of 2014 and chair of the UK government’s National Institute for Clinical Excellence (NICE) guidelines development group for Challenging Behaviour and Learning Disabilities (2013–2015). In 2013 Dr. Murphy was awarded the M. B. Shapiro Award for Clinical Psychology by the British Psychological Society. In 2014 she was elected a member of the Academy of Social Sciences. For many years, she has had research interests in challenging behavior, autism, sexuality, abuse, forensic issues, mental capacity, and the law in intellectual disabilities, and she has published over 130 journal articles, book chapters, and books on these topics.

Suzanne Nicholas is a Clinical Psychologist and works on the Wales Offender Personality Disorder Pathway, supporting probation officers in their work with high risk offenders who likely have a severe personality disorder. She completed her doctoral thesis concerning risk assessment of violence in offenders with intellectual disabilities at Cardiff University in 2008. As part of this research, Dr. Nicholas also developed a screening tool for risk assessment of violence, the RAPID, which is intended for community populations as it can be completed quickly, with limited information. She went on to demonstrate the reliability and validity of the RAPID for her doctorate in clinical psychology in 2012.

Raymond W. Novaco is Professor of Psychology and Social Behavior, at the University of California, Irvine, US. He has worked extensively on the assessment and treatment of anger with a variety of clinical populations, including forensic patients with intellectual disabilities in collaborative research with colleagues in Newcastle and Northumberland, UK. In 2009, he received the Academic Award from the Division of Forensic Psychology of the British Psychological Society. His coedited book, Using Social Science to Reduce Violent Offending (Oxford University Press) received the 2013 Best Book Award from the American Psychology‐Law Society.

Gregory O’Brien was Senior Psychiatrist with the Queensland disability services, Associate Professor at the University of Queensland, Australia and Emeritus Professor of Developmental Psychiatry at Northumbria University, UK. He was a specialist in learning disability, child and adolescent, and forensic psychiatry. Previously he held office as Associate Dean of the Royal College of Psychiatrists, President of the Penrose Society, Scientific Director of the Castang Foundation, Chair of the Faculty of Learning Disability of the RCPsych, and Associate Medical Director of Northumberland, Tyne & Wear NHS Foundation Trust.

John Rose is Director of the forensic clinical psychology training course and also works on the clinical psychology doctorate programme at the University of Birmingham, UK. Prior to this he has worked on the South Wales clinical psychology training course and as a clinical psychologist in a number of different clinical services. He has written on issues related to cognitive therapy, service design, offenders with learning disabilities and staff and organizational issues in intellectual disability services.

Robert J. Snowden is a Professor in the School of Psychology at Cardiff University, UK. He was educated at York and Cambridge Universities, UK and worked as a postdoctoral fellow at MIT in the US before going to Cardiff University. He was awarded a Personal Chair in 1999. Professor Snowden has published widely in the fields of visual perception, visual attention, and forensic and clinical psychology. He regularly contributes to professional training on risk assessment and forensic and clinical psychology. He has acted an advisor to both the UK and Welsh governments.

Jolene Sy is an Assistant Professor of Psychology at the University of Maryland, Baltimore County, US. Her research focuses on translational applications of behavior analysis within school settings with individuals diagnosed with intellectual disabilities.

Jenny Talbot joined the UK’s Prison Reform Trust in 2006 to manage the No One Knows Programme, which explored the prevalence and experiences of adult offenders with learning disabilities and difficulties. A series of research reports was published during this three‐year program, together with recommendations for policy and practice – a number of which have been adopted. She is currently director of the Prison Reform Trust’s Care not Custody program, which is concerned with people with mental health problems and learning disabilities who are in contact with criminal justice services. The program, which is chaired by Lord Bradley, has a particular interest in the development of liaison and diversion services for these individuals, and the government’s commitment for all police custody suites and courts to have access to them. In 2011 she received an OBE in recognition of her work on behalf of offenders with special needs.

Jon Taylor is a Consultant Forensic Psychologist and psychotherapist working in a medium secure service for offenders with intellectual disability and as head of psychotherapy at HMP Dovegate Therapeutic Community, Staffordshire, UK. He has provided consultation to the National Offender Management Service in the development of therapeutic communities for prisoners with a learning disability and led the development of a residential treatment programme for high risk offenders with intellectual disabilities and severe personality disorder at Rampton Hospital.

Ian Thorne, BSc (Hons), MSc, CBTPGDip, CPsychol, is a Principal Forensic Psychologist with Northumberland, Tyne & Wear NHS Foundation Trust, UK with responsibilities for coordinating treatment programs for detained offenders with intellectual and developmental disabilities. Prior to working in the NHS he fulfilled similar responsibilities within HM Prison Service.

Vasiliki Totsika is an Associate Professor at the University of Warwick. Her research on intellectual and developmental disabilities is across the lifespan and examines the role of the environment (family or staff carers) in determining the well‐being of people with an intellectual disability. She is particularly interested in longitudinal research and a large part of her work has focused on describing how challenging behaviors are developed and maintained over time.

Amanda L. Walker is a Clinical Psychologist currently working within a mental health recovery team at Derbyshire Healthcare Foundation Trust, UK. Prior to this she worked in locked psychiatric rehabilitation with offenders who have mental health difficulties and spent two years working in an acute inpatient unit. Her current interests are working with those individuals who have borderline personality disorders and complex trauma, using both dialectical behavior therapy and compassion‐focused therapy approaches.

Jessica R. Wheeler joined the Department of Psychiatry, University of Cambridge, UK as a Research Assistant on a Department of Health funded multisite pathway study of people with intellectual disabilities referred to services because of offending/offending‐type behavior. She completed her PhD on Environmental factors and alleged offenders with learning disabilities in 2011. Dr Wheeler then worked on a National Institute for Health Research (NIHR)‐funded project examining the provision of “good support” for people with intellectual disabilities who had contact with the criminal justice system. She then moved to the Institute of Criminology (University of Cambridge) as a Research Associate to work on a project concerning health and social care support for vulnerable populations with the Cambridge Migration Research Network.