The last 25 years of UK’s drug policy has been criticised as focusing on risk management, harm-reduction techniques and contributing to the criminalisation of the drug users whose treatment needs were not adequately addressed. Likewise,until recently research in criminal justice settings has been concentrating on evaluating treatment outcomes, often disregarding individual experiences and processes. Drug policy in the UK has recently undergone a historical shift, striving towards more person-centred practices that focus on recovery and ‘putting people first’. Along with the shift in the drug policy, there is a demand for research that individualises recovery processes and journeys and draws attention to examining personal and contextual factors that influence change. This thesis is part of the interest in individual experiences of addiction and recovery and focuses on delineating the process from one stage to the other. It is divided into two parts: the first part explores the process of change in a group of active users and users in recovery through the examination of their life stories. The second part explores the accounts of change in a group of substance using offenders in prison.Temporality is used as a methodological approach to examine change thoroughly across and at different points in time in order to understand drug using and recovery trajectories. The findings of the current study reveal change as a nonlinear process full of discontinuities, manifested in patterns of interchangeable states of relapse and abstinence or treatment attempts. The transition from addiction to recovery is achieved through the users’ participation in treatment groups that encourage the reconstruction of addict narratives to recovering ones.Analysis of the data collected in the prison confirmed the importance of relational factors in the adoption of new, healthier narratives. Moreover, it highlighted the significance of cultivating a climate of acceptance and support as an essential component of the therapeutic work conducted in prisons. The thesis serves as a critical body of work that links a multidisciplinary body of literature. The findings of the thesis contribute both to the academic knowledge in the fields of forensic psychology, addiction and criminology and provide essential knowledge to practitioners working with substance users both in the community and in the prison.