This study documents users' changes in psychological wellbeing across the lifecycle of their participation in an online community. Through in-depth interviews with 30 long-term users of Everything2.com, and content analysis of their posts, we found that psychological wellbeing plays a large role in the evolution of how users participate in the community over time. Everything2 is a long-running user-generated content site framed as an open encyclopedia. Results suggested that negative psychological wellbeing, such as loneliness and low self-esteem, fueled initial participation; validation and criticism from other users on one's content motivation continued content contribution; but ultimately feelings of relatedness with the community, unrelated to content contribution, was what retained users. Absence of social connections in the online community, as well as improved wellbeing offline, led to exit.