ABSTRACT This paper explores the significance of a tailored professional learning program (PLP) for transforming primary school teachers’ practices through fostering the development of professional capital; specifically human capital. The focus of the PLP was on assessing play and learning through play for Foundation teachers (the first year of formal schooling) in Victoria, Australia. Drawing from professional capital theory, the study engages with a significant issue through a mixed methods approach. Findings showed that the tailored PLP enhances teachers’ abilities to not only implement play-based learning but also to assess children’s play abilities and learning through play. The study underscores the importance of professional learning in facilitating teachers’ capacity to integrate play-based approaches into the curriculum effectively, while also identifying the tensions between teachers’ learning about assessment through play and navigating this approach in the classroom with competing external and mandated school policies. The paper adds to existing literature highlighting the pivotal role of professional learning when situated as a social practice in shaping teachers’ practices and confidence. It provides ways to promote reflective dis[positions which impact professional learning opportunities and processes, while also pointing to the transformative conditions of social arrangements and personal aspects that enable agency, collegiality and deliberation.