This volume contains the papers presented at the joint SUMo/CompoNet 2011 event: second international workshop on Scalable and Usable Model Checking for Petri nets and other models of concurrency and the first international workshop

SUMo and CompoNet PC members have reviewed nine submissions by researchers from several countries. Each submission was reviewed by 4 program committee members. Finally six papers have been selected for publication and presentation.

The Model Checking Contest is a SUMo's additional event that runs in parallel with the paper submissions, this year the results of this contest will be presented at the conference but not directly published in this proceeding. We expect a future publication of those results after the workshop.

The workshops organizers would like to thank Alexandre Duret-Lutz, from EPITA/LRDE for his Keynote talk entitled "Building LTL Model Checkers using Transition-based Generalized Büchi Automata".

The workshops organizers would also like to thank the authors of submitted papers for their interest in SUMo/CompoNet. We also thank the program committee members and the external reviewers for their outstanding work during the reviewing process.

Last but not least, we thank the authors of the EasyChair conference management system which made the practical organization of the reviewing process considerably easier.