We study how fairness perceptions during the early development of a technology venture do influence the degree of cooperation with the university, drawing on a sensemaking perspective. The analysis of the startup processes of 17 new ventures, consisting of 232 events, suggests that perceptions of unfairness tend to delay the new venturing process, as a result of decreasing cooperation. By contrast, perceived fairness involves a more rapid pattern of development. In general, this study shows how fairness perceptions co-evolve with the accumulation of experience, and how perceived fairness can turn into perceived unfairness and vice versa, and how this influences entrepreneurs’ cooperative behavior.