-- Software is increasing in size and complexity. As a direct implication, organizations nd it more difficult to achieve the desired product quality. Process improvement models are used to improve product quality. In recent years the combination of different improvement models is increasing. The main challenge in these environments is the interoperability of chosen models. An incorrect integration approach diminishes efficiency and effectiveness on applying these models. The general objective of this thesis is to identify principles and process characteristics for designing a system of processes at the architectural level. As a result of this research work, an improved understanding of improvement models interoperability is expected by identifying the technical and structural relationships between processes that will help architecting a system of processes. Software Engineering Management; Software Engineering Process