Since 1990 the International Workshop on Software Measurement (IWSM)has th been held annually and is now in its 19 edition. The International Conference on Software Process and Product Measurement (Mensura) was initiated in 2006 and is now in its third edition. The editions of IWSM/Mensura have been c- bined since 2007 to foster research, practice and exchange of experiences and best practices in software processes and products measurement. The 2009 e- tionswereheldduringNovember4-6,2009inAmsterdam, organizedjointlywith 1 The Netherlands Association for Software Measurement (NESMA) and kindly 2 hosted by Hogeschool van Amsterdam . Today the pressure for more e?cient software development processes del- ering appropriate quality is constantly increasing. But who knows how e?cient one's own current development process actually is and whether the quality of delivered products is really appropriate? Did we substantially improve with all the improvement e?ort spent? How can we answer all these questions if not by measuring both software processes and software products? Softwaremeasurement is a key technologywith which to manageand to c- trol software development projects. Measurement is essential of any engineering activity, by increasing the scienti?c and technical knowledge for both the pr- tice of software development and for empirical research in software technology. IWSM/MENSURAfacilitatestheexchangeofsoftwaremeasurementexperiences between theory and practice. Softwareprocessevaluationandimprovementrequirequanti?edmethodsand technologies. Issues such as the applicability of measures and metrics to so- ware, the e?ciency of measurement programs in industry and the theoretical foundations of software engineering have been researched in order to evaluate and improve modern software development approaches.