To achieve a complex value proposition, innovating firms often need to rely on other actors in their innovation ecosystem. This raises many new challenges for the managers of these firms. However, there is not yet a comprehensive approach that would support managers in the process of analysis and decision making on ecosystem strategy. In this paper, we develop a strategy tool to map, analyze and design (i.e., model) innovation ecosystems. From the scholarly literature, we distill the constructs and relationships that capture how actors in an ecosystem interact in creating and capturing value. We embed these elements in a visual strategy tool coined the Ecosystem Pie Model (EPM) that is accompanied by extensive application guidelines. We then illustrate how the EPM can be used, and conclude by exploring the multiple affordances of the EPM tool as a boundary object between research and practice.