Formal treatment (such as inpatient detoxification) often plays an important role in an individual’s addiction journey, but it is important to recognise that recovery from substance use disorder does not stop with formal treatment (Drug Strategy, 2017). This thesis investigated the attentional bias processes that can be used to predict treatment outcome after detoxification, and the experiences of individuals recovering from substance use disorders who were involved in a wide range of mutual aid groups. Previous research suggests that individuals with a substance dependency transition from identifying as an ‘addict’ to a ‘recovered’ individual, and that mutual aid groups play a significant role in this identity shift (Frings & Albery, 2015). The research in this thesis explored whether this identity shift could be detected through measuring individuals’ attentional bias processes towards identity-related words, and explored the beneficial nature of mutual aid groups and their role in maintaining recovery. Using the Stroop task, Study One assessed the relationships between clients’ attentional bias for alcohol and recovery-related stimuli, and their treatment outcomes. The results showed that an attentional bias for positive recovery-related words was the best predictor of treatment outcome after detoxification, with successful individuals having less attentional bias for these words than for the other word categories. Study Two aimed to qualitatively depict individuals’ experiences within social-based recovery groups. Four themes emerged from the semi-structured interviews with 10 group members: (a) the group’s role in their recovery, (b) personal choices and flexibility in the recovery experience, (c) group as an inclusive family unit, and (d) active involvement in the group. These themes provided an in-depth insight and highlighted the importance of socialbased groups for some individuals in recovery. The objective of Study Three (Part A) was to validate the Recovery Strengths Questionnaire (RSQ) as a new measure of recovery capital. The questionnaire was found to be psychometrically sound, with high internal consistency and concurrent validity with similar measures. RSQ scores were positively correlated with length of time both in recovery and in recovery groups. Factor analysis of the RSQ revealed a two-factor structure of recovery capital (‘internally generated recovery strengths’ and ‘externally generated recovery strengths’). Only internal strengths developed within recovery groups could predict length of time in recovery, and this finding emphasises the important role groups can play in developing recovery capital and helping sustain recovery. Study Three (Part B) used a survey to gain a first-hand perspective of the components that are offered and are considered important in recovery groups. Triangulation of the qualitative and quantitative data collected supported the presence and importance of the group components that have been suggested in previous literature (Moos, 2008). The qualitative results highlighted other important components of groups that were not identified in the previous literature, such as the presence of like-minded individuals, and an updated list of recovery group components was created. This updated list could be used to help develop new mutual aid groups, and evaluate the groups that are already established. Collectively, the findings from this thesis provide insight into the processes and experiences associated with the recovery pathway, and the identity transition from ‘addict’ to ‘recovering’ individual. The findings theoretically contribute towards the addiction literature, and have important clinical implications that can be used to help improve both substance misuse services and mutual aid groups.