In order to evaluate who benefits, and how, from collaboration between universities and society, it is necessary to develop solid evaluation models. The Swedish Governmental Agency for Innovation Systems (VINNOVA) has been commissioned by the Swedish government to present an evaluation model for university-society collaboration, which is intended to be included in the future distribution of funding to Swedish universities. This makes Sweden an interesting example of the challenges associated with the implementation of a national evaluation model for university-society collaboration. The objective of this study is to identify challenges for evaluation of university-society collaboration in an academic context. We analyse the actual implementation process of a national evaluation system for university-society collaboration, by putting Swedish policy in relation to international research. The results suggest that there is broad knowledge on the complexity of university-society collaboration, and of the difficulties associated with evaluation, even if certain aspects, like the importance of teaching, networking, and gender aspects, are often overlooked. However, the discussion tends to focus on the construction of relevant indicators, while there is a widespread lack of discussion and agreement on the objectives and goals of university-society collaboration, as well as discussions on how to define the concept. The importance of these aspects is illustrated by the difficulties in Sweden with developing a legitimate assessment system for university-society collaboration.