This book constitutes the thoroughly refereed post-proceedings of the 6th International Workshop on Software Composition, SC 2007, held in Braga, Portugal, in March 2007. The workshop has been organized as a satellite event of the European Joint Conferences on Theory and Practice of Software, ETAPS 2007.

The 15 revised full papers and 5 revised short papers presented together with the abstract of 1 invited talk were carefully selected during two rounds of reviewing and improvement from 59 submissions. The papers are organized in topical sections on composition contracts, composition design and analysis, dynamic composition, short papers, aspect-oriented programming, and structural composition.