This paper presents a model of the evolution of activities, risks, and required resources for innovative ventures. A key implication of the model is the importance of surprising events in the life of ventures. Such events happen in most innovative ventures and appear to be a major source of preventable failures. Reacting to these events requires significant inflows of new resources into the venture. However, inflows are usually prevented by the disconcerting effect of surprising events on venture participants and by the centrifugal reactions they trigger among participants. The model is used to provide recommendations for developing business plans elements that can diminish the impact of unexpected events on innovative ventures and can reduce the number of preventable failures