This paper takes a real options view of corporate venture capital (CVC), which are direct minority equity investments made by established companies in privately held entrepreneurial ventures. CVC investments have been characterized as creating growth options for corporate investors. We argue corporate investors often exercise these growth options by forming strategic alliances with their portfolio firms. We identify and empirically test a set of factors that lead established firms to exercise the growth options embedded in CVC investments by forming strategic alliances with the entrepreneurial ventures in which they invested. We explore how uncertainty surrounding a CVC investment influences the likelihood of future alliance formation.