Book excerpt: The book reveals the overall importance of a customer relationship management system especially for small and medium-sized enterprises. In addition to the topic of CRM, the increasing importance and possibilities of open source software is revealed.The main research question consists of the idea if open source customer relationship management systems are able to fulfill the requirements of a CRM software.In order to be able to answer this question, the following analysis made use of the literature available on the topics CRM, special requirements of small and medium-sized enterprises, and the topic of open source software.By revealing what a CRM have to fulfill in order to be classified as customer relationship management system according to the findings in the literature, various requirements are identified.In the next step, the three most popular open source CRM software systems Sugar CRM, vTiger, and OpenCRX are scrutinized under the criteria if they are able to fulfill the requirements defined in the previous steps.The conclusion discusses the previous findings and outlines the chances and limits of open source customer relationship management solutions for small and medium-sized enterprises.In addition to this, the requirements of a successful implementation of a CRM system are revealed and the concept of seeing CRM as a corporate strategy is concretized.The aim of this book is to outline the holistic approach of CRM and to examine the research question if open source CRM solutions are able to fulfill the requirements previously defined according to the underlying literature.