Purpose: The purpose of this study was to investigate the connection between professional development and professional capital within international schools in Asia. Design/methodology/approach: This study was an exploratory multisite case study. Teachers and leaders in six high performing international schools in Asia were surveyed to measure their professional capital. Three leaders with the highest professional capital from different schools were interviewed to better understand how professional development fosters professional capital of their teachers. Findings: International school leaders tended to have high professional capital while teachers reported having less professional capital. Leaders fostered professional capital of their teachers through professional development by supporting the intellectual passions of individuals, fostering collaborative learning within and across international schools and creating a culture of safety and vulnerability for teachers to try new things. Research limitations/implications: This study showed that a short version of the professional capital survey tested well in this context with items just focused on professional development. However, more work needs to be done to make the individual constructs more robust as it pertains to professional development. This research also highlighted the need to look at how international school teachers foster their own professional capital through professional development. Originality/value: This is the first study that focused on the intersection of professional capital and professional development. Additionally, this article serves as one of the few studies of professional capital in international schools.