This paper outlines the phenomenon of Inner
Source software development and places it in the context of existing open source literature. Our study includes an analysis of multiple case studies of Inner
Source in use in large scale global software
development companies. The lessons learned from these case studies help us to contrast traditional open source principles with Inner Source principles, and we then gather these lessons, to create our preliminary
framework, in order to make sense of when and how firms can adopt Inner Source. Our framework helps to make sense of the practical issues of adopting and
managing Inner Source. We have highlighted the emerging trends in the Inner Source phenomenon and surrounding areas. Awareness of this may be of great benefit to researchers in the area and industrial
practitioners.