This volume contains the proceedings of the 3rd Workshop on Model Driven Tool and Process Integration held on 16 June 2010 in Paris, France, in conjunction with the European Conference on Modeling Foundations and Applications (ECMFA 2010). The 1st workshop held in 2008 has shown that the research area of tool and process integration in a model-driven development environment is emerging and draws more and more attention in particular from industry. The 2nd workshop was held in Enschede 2009. The focus of this workshop was on synchronization, the efficient computation of model-differences as well as the usage of model repositories. The interesting talks and discussions of these events have encouraged us to organize a third edition of the workshop. The papers included in this year's edition of the workshop show that there are a variety of relevant topics in this field. The integration of data from different tools with traceability support is still an important problem. Interestingly, papers describe different approaches to handle this problem. Furthermore, the integration of development processes and development teams is covered by papers of this workshop edition. Moreover, results of research projects are presented which have related topics in their objectives.