Book excerpt: Understanding and Working with Substance Misusers explores the complex nature of addiction and the challenges involved in responding effectively through policy and practice. It examines the biopyschosocial elements of addiction to substances (including alcohol) and, draws together key research findings from these fields to present a new framework for integrating theory and practice. The book argues that the best way to understand addictions is as examples of "complex self organising systems", which comprise many interacting component parts. In so doing, it addresses the problem of service users presenting with multiple needs (including poly drug use, mental health problems, criminal behaviour, unemployment and relationship difficulties) and the challenges that this poses for policy makers, services commissioners and practitioners alike. This book fills the need for a text which makes the complex issues surrounding substance misuse accessible to both students and practitioners. As such, it fosters a multidisciplinary and critically reflective approach to policy and practice.