For over a decade, software process improvement (SPI) has been promoted as an approach to improve systematically the way software is developed and managed. Mostly this research and the relevant experience reports have been focussed on large software companies.Conradi and his co-authors have collected the main results from four Norwegian industrial research and development projects on SPI carried out between 1996 and 2005, which, in contrast to other treatments, concentrated on small- and medium-sized companies, typically characterized by fast-changing environments and processes. The presentation is organized in five sections: general principles and methods of SPI, knowledge management for SPI, process modelling and electronic process guides, estimation methods, and object-oriented and component-based systems. A spectrum of empirical methods has been used, e.g. case studies, large-scale experiments, surveys and interviews, and action research.The book mainly targets researchers and graduate students in (empirical) software engineering, and software professionals working in development or quality assurance.