The “Lose Weight, Feel Great” (LWFG) pathway was commissioned by NHS Ashton, Leigh & Wigan with the aim to reduce the rising tide of obesity within the Wigan Borough (Hogg et al. 2010). The Community Weight Management Programme (CWMP) is one of the services offered and involves dietary advice, physical activity sessions and methods for behavioural change. Approximately 35% of service users are successful at losing 5% or more of their initial body weight; however other service users are not as successful. The aim of this dissertation was to understand the context and mechanisms which may facilitate or impede success. Method: Following a framework of Realistic Evaluation (Pawson & Tilley, 1997), 25 semi-structured telephone interviews where undertaken with people who had previously accessed CWMP. The interviews where transcribed verbatim and then analysed using Thematic Analysis to identify common themes (Howitt & Cramer, 2007). Findings: Seven Themes emerged from the interviews. Four themes related to mechanisms of CWMP, two themes related to contexts surrounding CWMP and one theme related to outcomes from CWMP. Mechanisms involved: group sessions; Slimming World consultant & Wigan Leisure Culture Trust activity officers; physical activity sessions; the Slimming World Eating Plans. Contexts involved: the Healthy Foundations Segmentation Model; motivation & Readiness to Change. Outcome: Change in Lifestyle. Conclusion: Changes could be made to CWMP, such as increasing the number of free sessions, offer other LWFG services if CWMP does not appear to be appropriate, and provide more extensive information during the induction sessions. However, it is also important to take into account people’s motivation to change, the segment that they may fit into and that changes to lifestyle are not just limited to the service users, but also family members. Changes to the programme will improve success rate and ensure that resources are used effectively.