This book constitutes the refereed proceedings of the 13 International Conference on Product-Focused Software Process Improvement, PROFES 2012, held in Madrid, Spain, in June 2012. The 21 revised full papers presented together with 3 short papers and 4 workshop and tutorial papers were carefully reviewed and selected from 49 submissions. The papers are organized in topical sections on process focused software process improvement, open-source agile and lean practices, product and process measurements and estimation, distributed and global software development, quality assessment, and empirical studies.