During his PhD studies, Claus Ballegaard Nielsen researched how computer models can be used to ease the integration and collaboration challenges that engineers face during the development of Systems of Systems. Multiple approaches for improving the tool-support for formal modelling techniques in System of Systems Engineering was developed during his studies. His research is focused on three areas: managing integration challenges in System of Systems engineering, enhancing the capabilities of System of Systems modelling and enabling collaborative development in formal modelling.