This doctoral dissertation aims to understand how companies realize corporate responsibility - both how they perform corporate responsibility in particular local contexts and how they negotiate understandings of what corporate responsibility means. It builds on an inductive case study of the Danish pharmaceutical company Novo Nordisk, a company known for its remarkable investments in integrating societal objectives into its business model and promoting new ways of thinking about and doing business. The case inspired the overarching theoretical question how actors construct and legitimize new ideas and practices at the nascent stages of institutional change. To address this question, the dissertation develops a micro-sociological approach to institutional change that brings to light how actors struggle over meaning in power relations by focusing on processes of positioning and framing. The three articles in this dissertation unfold distinct yet interdependent processes of positioning and framing that constitute new ways of performing and understanding corporate responsibility.