In this exploratory case study, I examined how preservice music teachers (PMTs) developed collective free music improvisation (CFMI) competencies in a teacher training program in Singapore. Nine PMTs participated in the 6-week course, where they acquired CFMI skills following a curriculum derived from improvisation and free improvisation literature. Data obtained through video recordings of course proceedings, field notes, interviews, and surveys were analyzed through the constant comparative method of analysis. Findings revealed PMTs' learning processes as a 3-part journey based on recurring behavioral traits in each segment. Over weeks of performances, PMTs transitioned from a conservative behavioral state to an increasingly volatile one that challenged socio-musical boundaries, finally establishing unique group identities at the end of their journey. Based on their learning experiences, I provide suggestions to scaffold CFMI training.