This book constitutes the thoroughly refereed post-proceedings of the First International Symposium on Generative and Component-Based Software Engineering, GCSE'99, held in Erfurt, Germany, in September 1999. The 15 thoroughly revised full papers presented together with an invited paper have gone through two rounds of reviewing and improvement. The book offers topical sections on aspects, generative approaches, language composition, component-oriented language idioms, and domain analysis and component-based development.