  Several open source software (OSS) projects expect to foster newcomers'
onboarding and to receive contributions by participating in engagement
programs, like Summers of Code. However, there is little empirical evidence
showing why students join such programs. In this paper, we study the
well-established Google Summer of Code (GSoC), which is a 3-month OSS
engagement program that offers stipends and mentors to students willing to
contribute to OSS projects. We combined a survey (students and mentors) and
interviews (students) to understand what motivates students to enter GSoC. Our
results show that students enter GSoC for an enriching experience, not
necessarily to become frequent contributors. Our data suggest that, while the
stipends are an important motivator, the students participate for work
experience and the ability to attach the name of the supporting organization to
their resum\'es. We also discuss practical implications for students, mentors,
OSS projects, and Summer of Code programs.
