Against the backdrop of increasing product complexity, shorter innovation cycles, and consistently high quality requirements for supplier products, quality control in development projects is gaining importance. Many companies have responded to this development by establishing methods for project quality control in their development processes. These are referred to as Quality Gates or Stage Gates, among other terms. However, methodological standards for such gateway systems have not yet been developed, resulting in significant variations in the implementation of project quality control in practice. This book aims to fill this gap and develop a guide for the self-assessment of gateway systems in the supplier industry. The underlying self-assessment model is based on the already established Excellence Model of the EFQM.