These are the refereed proceedings of the 23rd International Conference on Application and Theory of Petri Nets, ICATPN 2002, held in Adelaide, Australia, in June 2002. The 18 regular papers and one tool presentation presented together with six invited paper were carefully reviewed and selected from 45 submissions. All current issues on research and development of Petri nets are addressed, in particular concurrent systems analysis, model validation, business process management, reactive systems, workflow processes, wireless transaction protocols.