As a major component of leadership development, professional development (PD) support needs more researchers to focus on possible ways to build school leaders' instructional capacity. Despite the increasing use of virtual professional development (VPD) as venues for leadership development, little is known about the essential components of an effective VPD. With the advent of COVID-19, we pivoted to VPD focused on improving school principals' abilities to help teachers increase their instructional capacity. More specifically, we provided a virtual Summer Leadership Institute (VSLI) on peer coaching via VPD. Since research on effective PD calls for school leaders to translate their learning into leadership practice, we addressed in our sequential explanatory mixed methods study how practicing school leaders in the United States perceived the effectiveness of VPD on school leaders' professional knowledge and growth related to the VPD topic of peer coaching. We conclude with seven specific principles to consider when developing and providing such a VPD experience for school leaders.