This book constitutes the refereed proceedings of the Third International Conference, ICMT 2010, held in Malaga, Spain, in June 2010. The 17 revised full papers were carefully revised and selected from 58 submissions. The scope of the contributions ranges from theoretical and methological topics to implementation issues and applications. The papers include different issues related with: Search Computing, Composition of Model Deltas, Testing Model Transformation, Safe Composition of Transformations, Model-to-Model Transformations and Model Migration of Epsilon Flock