Successful Free/Libre and Open Source Software (FLOSS) projects incorporate both habitual and infrequent, or episodic, contributors. Using the concept of episodic volunteering (EV) from the general volunteering literature, we derive a model consisting of five key constructs that we hypothesize affect episodic volunteers’ retention in FLOSS communities. To evaluate the model we conducted a survey and received responses from over 100 FLOSS episodic volunteers. We observe that three of the constructs (social norms, satisfaction and community commitment) are all positively associated with volunteers’ intention to remain, while the two other constructs (psychological sense of community and contributor benefit motivations) are not. Furthermore, exploratory clustering on unobserved heterogeneity suggests that there are four distinct categories of volunteers: satisfied, classic, social and obligated. Based on our findings, we offer suggestions for projects to incorporate and manage episodic volunteers, so as to better leverage this type of contributors and potentially improve projects’ sustainability.