How to encourage university-community engagement with local communities and disadvantaged groups?  This is one of the main questions of the project LASIN – Latin American Social Innovation Network. Specifically, one of the main activities of LASIN is to design and run what are called SISU – Social Innovation Support Units, i.e., units dedicated to support the promotion of social innovation processes between university community members and external actors. Universities are privileged contexts for the experimentation of creative projects in social innovation if the focus is placed on fostering the interaction between internal and external actors, which can be significantly empowered by design practices. The specific objective of this paper is to describe a model for the SISU operation together with principles based on the design approach to social innovation. The recognition of the importance of the design in the promotion of social innovation has been particularly highlighted through the activities of DESIS (Design for Social Innovation Network).