This contains the papers presented at DCM 2018, the 12th International Workshop on Developments in Computational Models. The event, taking place on July 8, 2018, is as a one-day satellite event of FLoC 2018 in association with the ACM/IEEE Symposium on Logic in Computer Science (LICS) and the  International Conference on Formal Structures for Computation and Deduction (FSCD).

Several new models of computation have emerged in the last years, and many developments of traditional computation models have been proposed with the aim of taking into account the new demands of users of computer systems and the new capabilities of computation engines. A new computation model, or a new feature in a traditional one, usually is reflected in a new family of programming languages, and new paradigms of software development. The aim of this workshop is to bring together researchers who are currently developing new computation models or new features for traditional computation models, in order to foster their interaction, to provide a forum for presenting new ideas and work in progress, and to enable newcomers to learn about current activities in this area.

The program committee selected six papers for presentation at DCM 2018. In addition, the program includes invited talks by Delia Desner (joint ITRS/DCM invited speaker), Ugo Dal Lago and Damiano Mazza (also, joint ITRS/DCM invited speaker). The final proceedings of DCM 2018 will appear as a volume of Electronic Proceedings in Theoretical Computer Science.

We wish to thank the organizers of FLoC 2018 for their support. We are indebted to the program committee members and the external referees for their careful and efficient work in the reviewing process.  Finally we are grateful to the authors for submiting their work and the invited speakers for sharing their knowledge.