This publication-based dissertation investigates how firms of different sizes and structures manage simultaneous cooperation and competition (coopetition). It includes five self-contained research papers, four designed for publication in peer-reviewed academic journals, and one developed for publication as an academic teaching case study. The first paper is a systematic literature review that identifies recent accomplishments and future trends in coopetition research. It delivers a comprehensive, unique, and updated view on the field, unifying scattered research findings into a cohesive and overarching framework. The second paper is a single-case study, zooming in on the inner workings of a corporate incubator. It explores the role and management of internal coopetition to develop entrepreneurial competencies for business model innovation. The third paper shifts the research focus toward large multinational enterprises to explore the formation of new coopetition relationships. It illuminates a new organizational design and accompanying management principles to address paradoxical tensions in the first and potentially most difficult phase of coopetition. The fourth paper taps into the complexities of coopetition between small- and mid-sized firms and large corporates. It uncovers three coopetition strategies and a mix of management principles for smaller firms to navigate asymmetrical risks in coopetition with larger companies. The fifth paper expands the scope of the dissertation to include an entire industry, analyzing the drivers, strategies, and outcomes of coopetition in a highly concentrated and regulated sector. Taken together, the five research papers collectively contribute to a more nuanced understanding about the management of coopetition and provide valuable implications and recommendations for practitioners.