This study describes pre-service teachers’ and collaborating teachers’ perspectives of a professional development training, which focused on co-planning and co-teaching in secondary mathematics. Data were garnered from 19 pre-service teachers and 23 collaborating teachers, using a pre-survey, a professional development survey, and personal reflections. The quantitative data were analyzed using descriptive statistics, and the qualitative data were analyzed using a constant comparative analysis. The findings suggest that the professional development helped participants conceptualize how co-planning and co-teaching could be enacted during clinical experiences. We also found that all participants valued collaboration and communication opportunities, hands-on activities, and providing explicit examples for a mathematical context. The collaborative pairs noted they wanted to have more opportunities to engage in co-planning to better enact the co-teaching strategies. The findings of this paper have implications for teacher preparation programs, which seek to prepare pre-service teachers and facilitate professional development training for collaborating teachers and pre-service teachers.