Important changes in the strategies ofsuppliers and buyers of Complex Product Systems can be empirically observed. Buyers are increasingly outsourcing activities previously performed by themselves, forcing suppliers to move away from their traditional role as system integrators towards that of offering an enlarged set ofservices. The purpose ofthis paper is to find theoretical insights that can help in explaining these strategic changes, as well as the process of acquiring organizational capabilities by suppliers of these services. These moves are contributing to change market structures. Transaction Costs Theory, alongside the evolutionist conception and Chandler's organizational-historic perspective, are the routes explored to explain this dynamic behavior
