Make-believe play (MBP) provides kindergarteners with an authentic form of engagement that is particularly favourable to the development of oral and written language. As part of an action research study, an activity-oriented professional development (PD) program incorporating video was established to provide kindergarten teachers with guidance on their teaching practices in MBP situations. The findings show changes in the participant's PD trajectories. These findings provide direction as to how teachers who wish to implement more MBP practices in the classroom to promote language development in children can be supported within the framework of such a program. For instance, the results match those of previous research as regards whether a program that uses evidence such as videos would be more effective in leading a participant to effect changes in their PD. The results also indicate that PD programs cannot be exclusively collective or individual, but benefit from combining the two approaches.