This book constitutes the refereed proceedings of the 19th International Conference on Product-Focused Software Process Improvement, PROFES 2018, held in Wolfsburg, Germany, in November 2018. The 16 revised full papers and 8 short papers presented together with 10 workshop papers and 2 industry talks were carefully reviewed and selected from 65 submissions. The papers are organized in the following topical sections: processes and methods; empirical studies in industry; testing; measuremene and monitoring; and global software engineering and scaling. Further relevant topics were added by the events co-located with PROFES 2018, the Second International Workshop on Managing Quality in Agile and Rapid Software Development Processes (QUASD) and the Third Workshop on Hybrid Software and System Development Approaches (HELENA).