Understanding why individuals choose to get, and stay, involved in public participation in science research is essential to building and maintaining the strong base of participants required for many research and conservation efforts. This paper explores the differences between initial and sustained motivations of volunteers working in more- and less- intensive environmental citizen science projects in the Mid Atlantic United States. Results from our mixed-methods study show that volunteers endorse different motivation types depending on how the question is asked (survey versus semi-structured interview), and that volunteer motivation varies by program type. Although survey results did not show differences in motivation over time, interview responses indicated a potential shift from more egoistic to more collectivistic motivations. These findings connote implications for volunteer recruitment and retention including the importance of developing appeals that explicitly connect volunteer opportunities to both personal pleasure and to the support of a universal good.