The concept of open innovation has predominantly been used in the innovation management field rather than in the entrepreneurship field. The aim of this chapter is to review the entrepreneurship literature related to cross-boundary knowledge flows, and in doing so bridge the important gap between entrepreneurship research and research on open innovation. This chapter distinguishes between the enablers of cross-boundary knowledge flows in new ventures and how such knowledge flows unfold throughout the venture creation process, as well as showing how they are linked to the creation of high-growth ventures. Future research can examine how open innovation supports new ventures in not only achieving financial returns but also in scaling their social and environmental impact. In effect, by innovating openly, new ventures may achieve economic growth and, in parallel, tackle grand societal challenges.