Enrollment at university can be based on personal interests (intrinsically motivated) as well as financial prospects (extrinsically motivated). I investigate whether and how these qualities of motivation for enrollment influence achievement motivation and well-being of university students at the beginning of their studies. Thereby, I relied on data from a longitudinal study in which university freshmen were questioned at the beginning and end of their first academic year. The results of the study indicate that intrinsic motivation for enrollment facilitates the development of a learning goal orientation and retrospective satisfaction with choice of major. Extrinsic motivation for enrollment was related to impaired study satisfaction over time and enhanced thoughts about dropout. These prospective effects were robust when controlling for initial individual differences in achievement goal orientations, life satisfaction, and GPA. The presented research provides new insights regarding how educational decisions affect achievement motivation and well-being in educational contexts over time.