Research foundations for system of systems engineering

System of systems engineering (SoSE) continues to evolve as a potentially promising response for analysis, design, and transformation of increasingly complex systems problems. The purpose of this paper is to establish critical foundations and offer a coherent framing for further research in SoSE. To achieve this purpose the paper is organized to: (1) introduce a contemporary perspective of SoSE, focused on identifying both convergence and divergence in the literature, (2) develop five logical levels that can help to understand divergence in SoSE and sharpen future research efforts, (3) articulate several of the critical research challenges that SoSE must address to be viable, and (4) identify a preliminary set of critical topical research areas for development of a more integrated research agenda for SoSE. The paper concludes with implications for close coupling of research and practice for the accelerated development of SoSE through an integrated research agenda.