Purpose The third mission mandate is a significant mission evolution for universities and is being driven by environmental and stakeholder pressures to deliver economic and social impact through research commercialisation, knowledge and technology transfer. It also challenges the traditional institutional logics of universities. Drawing on institutional theory, specifically institutional pressures and competing logics, this paper examines how university leaders interpret their third mission mandate and explores the initiatives they prioritise to advance it. Design/methodology/approach Set in an Irish context, this study adopted grounded theory using phenomenological interviews with 15 senior university leaders in Ireland. Findings The study finds that university leaders' interpretations of institutional pressures and competing logics generate an analytically derived range of four strategic postures: Reactive Responders, Cultural Champions, Infrastructure Builders and Ecosystem Orchestrators. These postures differ in the scope of intrapreneurial response, the extent to which academic and entrepreneurial logics are integrated and the degree of external orientation. The findings explain how leadership interpretation and institutional work contribute to heterogeneous university responses to the third mission.