Mathematical and stochastic computer models were built to simulate concurrent engineering processes (CE) in order to study how different process mechanisms contribute to new product development (NPD) performance. .tviicro-models of various phenomena which occur in concurrent engineering processes, such as functional participation, overlapping, decision-making, rework, and learning, were included, and their effects on the overall NPD process were related to process span time and effort. The study focused on deterrnining under what conditions CE processes are more favorable than sequential processes, in terms of expected payoff, span time, and effort, as dependent variables of functional participation and overlapping, and the corresponding trade-offs between more upfront effort versus span time reduction.