This study investigates student teachers' emotions about their upcoming team practicum. The theoretical foundation grounds in the FIT-Choice approach (Watt, H. M. G., and P. W. Richardson. 2008. "Motivations for Teaching: Theoretical Perspectives and Empirical Findings." "Learning and Instruction" 18: 405-98) and in control-value theory (Pekrun, R. 2006. "The Control-Value Theory of Achievement Emotions: Assumptions, Corollaries, and Implications for Educational Research and Practice." "Educational Psychology Review" 18: 315-41). We examined 405 Swiss student teachers who answered open- and close-ended questions. The quantitative results show that students' beliefs in their teaching and their teamwork skills were significantly related to positive and negative affect; this was also supported by the qualitative data. Further, student teachers experienced more positive affect if they had chosen teaching due to intrinsic reasons. The qualitative results reveal that the quality of relationships in the team practicum must be regarded as another significant source of emotions.