Collaboration is essential in learning ensemble music. It is unclear, however, whether an individual benefits more from collaborative or individual rehearsal in the initial stages of such learning. In nonmusical domains, the effect of collaboration has been mixed, sometimes enhancing and sometimes inhibiting an individual's learning process. In music, observational studies suggest collaborative rehearsal is indeed effective. In the present study, we compared collaborative and individual rehearsal directly and experimentally. Vocalists studied some pieces alone (with or without accompaniment) and some pieces collaboratively in groups of three. Their immediate performance and memory results indicated that accompaniment in solo sessions enhanced individual learning, and more importantly, collaboration had a detrimental effect. The findings are discussed within the general framework of blocking or free-riding theories.