This study explores the development of student teachers' skills in implementing collaborative learning (CL) using a multilevel repeated measures design. Participants were 105 pre-service teachers that were trained in CL implementation. The results indicate that student teachers generally perform well in implementing CL. Further, it appears that these skills increase over time, although no linear growth can be found. Student teachers' skills development appears to be positively connected with their general feeling of teaching efficacy. Surprisingly, training and students' pedagogical knowledge have no significant impact. (Contains 1 figure and 4 tables.)