The workshop OCLApps 2006 was organized as a part of MoDELS/UML Conference in Genova, Italy. It continues the series of five OCL (Object Constraint Language) workshops held at previous UML/MoDELS conferences between 2000 - 2005. Similar to its predecessors, the workshop addressed both people from academia and industry. The advent of the MDA (Model Driven Architecture) vision and the rapid acceptance of MDE (Model Driven Engineering) approaches emphasize new application domains (like Semantic Web or Domain Specific Languages) and call for new OCL functionalities. In this context, the OCLApps 2006 Workshop, was conceived as a forum enabling researchers and industry experts to present and debate how the OCL could support these new requirements.