Purpose: This paper aims to address workplace learning in terms of investigating school leadership development in an inter-professional team (the team) in which principals, administrators and researchers work together on a local school improvement project. The purpose is to provide an enriched understanding of how school leadership development evolves in a team during two years as the team works on different problem-spaces and the implications for leadership in schools. Design/methodology/approach: The paper is based on a larger study with a qualitative research design with longitudinal, interventional, interactional and multiple-time level approaches. Empirically, the paper draws on tools, video and audio data from the teams' work. By using cultural-historical activity theory (CHAT), school leadership development is examined as an object-oriented and tool-mediated activity. CHAT allows analyses of activities across timescales and workplaces. It examines leadership development by tracing objects in tool-mediated work and the ways in which they evolved. The object refers to what motivates and directs activity. Findings: The findings suggest that the objects evolved both within and across episodes and the two-year trajectory of the team. Longitudinal trajectories of tools, schools and universities seem to intersect with episodes of leadership development. Some episodes seem to be conducive for changes in the principals' schools during the collaboration. Research limitations/implications: There is a need for a broader study that includes more cases in other contexts, thus expanding the existing knowledge. Originality/value: By switching lenses of zooming, it has been possible to examine leadership development in a way that is not possible through surveys and interviews.