This document discusses using Bayesian belief networks to model construction schedule delays. It presents the objectives of identifying risk factors for delays and evaluating their probability of causing delays. It then reviews relevant literature on risk analysis and Bayesian belief networks. The document outlines developing a Bayesian belief network model for a construction project by collecting data on risk factors and their impacts, and analyzing the probabilities of factors and delays. The model can estimate delay probabilities even with incomplete data. The conclusion is that the model helps managers mitigate risk factors and avoid schedule growth.