Model-based approaches such as Model-BasedSystems Engineering (MBSE) are widely regarded as a necessity to enable and support the development of ever more complex Systems of Systems (SoS). A key to the application of modelbased development approaches in companies is the introduction of systems engineering architecture frameworks (SEAF) to structure the models of systems to be developed. This paper displays the research to develop a SEAF for SoS. Through workshops and interviews with 18 partners from industry and research, we derived perspectives to be considered for describing and modeling SoS. By analyzing existing SEAFs from literature we concluded, that not all perspectives we identified as relevant are covered by a single framework. Based on our research, especially the explicit consideration of SoS characteristics such as autonomy and interdependence, the integrated consideration of product, production system and validation system development, as well as consideration of different product generations and (re-)use of models appears to be not profoundly addressed. Advancing the state of research, we therefore propose a six-dimensional SoS engineering architecture framework to cover all perspectives we identified as relevant. The proposed framework can further serve as a reference for developers to derive and build specific frameworks tailored to their needs while at the same time supporting consistency, reusability and compatibility of the specific frameworks. The presented framework is an initial proposition which continuously being used and evaluated by its application to structure modeling for a variety of real systems from different industries. Insights from the application are fed back for its further development.