This chapter explores the ownership heterogeneity of collaboration in entrepreneurial ventures over time. First, it adopts a temporal perspective to examine two aspects of traditional entrepreneurial start-up activities: the evolution of collaboration in the entrepreneurial team in a particular venture over time and the evolution of collaboration as habitual entrepreneurs develop the portfolio of ventures they own over time. Second, it takes a temporal view to examine the nature of collaboration in entrepreneurial ventures in different environmental contexts, specifically, academic spin-offs, secondary management buyouts/buy-ins, and returnee entrepreneurs. These contexts represent cases where the nature and challenges of collaboration may be quite distinct from that in traditional commercial start-up ventures in developed economies. Third, it examines the temporal dimensions of collaboration in different forms of the financing of entrepreneurial ventures. A final discussion section considers directions for future research.