Objectives: The research aimed to analyse retirees' experiences of a tailored positive psychology intervention (PPI) combining Best Possible Self (BPS) expressive writing with goal-setting and to explore its potential as an aid to retirement wellbeing. This is the first time, to our knowledge, that BPS and goal-setting have been employed as a combined approach. Design: This was an experimental study design using qualitative analysis methods, namely interpretative phenomenological analysis, alongside participatory action research. Methods: Three recently retired women participated in the project. Semi-structured interviews and groups were used. Results: The intervention contributed to feelings of retirement wellbeing by boosting a number of meaning-related factors (such as self-awareness, purpose in life and intrinsic goal-progress), bringing about an overall improvement in hedonic-eudaimonic balance. Conclusions: Findings suggest a need for further research into the newly combined intervention and into its most appropriate delivery format(s) for retirees (e.g. online versus face-to-face). Given the intervention's potential to elicit wellbeing-maximising goals, the current findings have relevance for populations beyond the retiree community.