In most software organizations, the budget for software maintenance is much larger than for software development. However, there is much less management attention focus on software maintenance than on software development. This book illustrates how process improvement models popular with software development can be applied to software maintainers. In particular, this book presents a new way of capturing the uniqueness of software maintenance activities in a model-based process improvement approach. The focus of this book is, therefore, on the uniqueness of software maintenance activities, on how to assess the software maintenance using the Software Maintenance Maturity Model (S3m model) and how to figure out improvement paths.