The main aims of the series of volumes "Advances in Petri Nets" are: - to present to the "outside" scientific community a fair picture of recent advances in the area of Petri nets, and - to encourage those interested in the applications and theory of concurrent systems to take a closer look at Petri nets and then join the group of researchers working in this fascinating and challenging area. The ESPRIT Basic Research Action DEMON (DEsign Methods based On Nets) has been a focus of developments withinthe Petri net community for the last three years. The papers presented in this special volume have been selected from papers submitted by participants in DEMON. The papers have been refereed and appear in revised form. The volume contains technical contributions giving insights into a number of major achievements of the DEMON project. It also contains four survey papers covering important research areas. The volume begins witha description of DEMON given by its coordinator E. Best.