Traditional models for project management have not adequately incorporated a number of factors that are important for resource allocation. This paper describes the use of Petri nets to facilitate resource allocation in projects under some conditions commonly encountered in practice. Petri nets provide a powerful formalism for representing and analyzing concurrent systems. To date, however, very little has been done to integrate this graphical and mathematical tool with the area of project management. Petri net models can be used to analyze interdependencies, criticality, substitution, conflicting resource priorities, and variations in the availability of resources. This paper proposes a new model and demonstrates the usefulness of the model for real-time activity scheduling in a resource-constrained project environment. The model has been computerized using C language, and a simple project is chosen as an example to provide step-by-step explanations of the simulation carried out. This paper also discusses the implications of the model and the analysis it supports. © 1998 IEEE.