This chapter contributes to the recent line of work examining entrepreneurs who participate in multiple ecosystems simultaneously by investigating the mechanisms and outcomes of AppCampus. The AppCampus initiative was a three-year project seeking to leverage and enhance both the entrepreneurial ecosystem around Aalto University and the Windows Phone innovation ecosystem. The authors briefly review the characteristics of both innovation and entrepreneurial ecosystems, followed by an analysis of the Windows Phone ecosystem and the Aalto entrepreneurial ecosystem. They then describe the AppCampus initiative, explaining each of its components and how these linked both the Windows Phone innovation and Aalto University entrepreneurial ecosystems, before discussing the effects that AppCampus had on these ecosystems. The chapter concludes with lessons for both entrepreneurial and innovation ecosystem leaders.