This thesis aims to understand the presence of psychological ownership within an online brand community. Psychological ownership is becoming increasingly relevant in marketing, being able to provide benefits to both consumers and firms. Firms should therefore attempt to facilitate and capitalise on psychological ownership in their consumers. Brand communities are becoming a more and more common platform for consumers of a brand to use for information and interaction with the brand and other enthusiasts. Due to the strong feelings that brand community members generally have towards the focal brand, it is likely that psychological ownership feelings may also develop towards the brand. Therefore it is important to understand how psychological ownership can develop in a brand community context, and also how it can manifest in the attitudes and behaviours of members. To achieve this aim, the present study used a grounded theory approach to guide the use of a single-case study. This enabled the gathering of comprehensive, qualitative data to discover new theory about the phenomena. The case study used was the online Volkswagen brand community, and members’ responses to the diesel emissions crisis of 2015/16. Data was collected in the form of Facebook comments in the Volkswagen online brand community. A total of 355 responses were thematically analysed before theoretical saturation was reached. The results of the study found evidence of existing psychological ownership elements. Two of the routes to psychological ownership were identified within the brand community; coming to intimately know, and investing the self into the target of ownership. Additionally the outcomes of organisational commitment, citizenship behaviour, sense of loss, and escalation of commitment were proven to exist in the brand community. The study also presented new findings in relation to the little-studied collective psychological ownership and blame-shifting as a potential form of escalation of commitment. The major conclusions that can be drawn from the present study are of significance to the marketing literature. Psychological ownership can occur towards a brand, and within the context of a brand community, thus opening the door for further research within these constructs. Based on the present study, it is recommended that managers attempt to facilitate psychological ownership within their own brand’s communities. Actions by firms such as facilitating interaction between members, asking members for help and ensuring favourable change processes is important in order to create and maintain consumer psychological ownership, while providing a positive workplace can ensure psychological ownership of their employees.