The main goal of this paper, based on a content analysis of the literature about models of inter-institutional collaboration between higher education institutions, is to establish the characteristics that set them apart, contextualize each of these models in terms of the features of the setting in which they are implemented, and ascertain their advantages, drawbacks and potential benefits for the institutions that use them. This has involved employing appropriate keywords to identify the most relevant studies that have examined models of inter-institutional collaboration. The paper concludes that detailed study is required when choosing a particular model of inter-institutional collaboration, especially mergers, as the desired economies of scale do not always materialize, research and teaching results may not improve and it is unclear what the optimal size for achieving efficiency is.