Collaboration patterns are an efficient way to define, reuse and enact collaborative software development processes. We propose an approach to define and apply collaboration patterns at modelling, instantiation or execution time. Our patterns, inspired from workflow patterns, are described in CMSPEM, a Process Modelling Language developed in our team. In this paper, we briefly describe the CMSPEM metamodel and focus our presentation on two collaboration patterns: Duplicate in Sequence with Multiple Actors, Duplicate in Parallel with Multiple Actors and Merge. The approach is illustrated by a case study concerning the collaborative process “Review a deliverable”