This article presents a framework for structuring and supporting the complex and dynamic process of alliance building. Fit is the key concept in this framework, which is based on an extensive literature study and in-depth case studies. The concept of “fit” is not new in itself. The added value of this article is, firstly, that it identifies different aspects of fit and their interrelationships, as well as providing an insight into the drivers for fit. Here, we focus on strategic and organisational fit in particular. Secondly, we make practical recommendations for alliance managers on how to actually manage fit.