This article provides an overview of the theory of collaborative advantage. This is a practice-oriented theory concerned with enhancing practical understanding of the management issues involved in joint working across organizations. Two contrasting concepts are central to it: collaborative advantage which is concerned with the potential for synergy from working collaboratively; and, collaborative inertia which relates to the often disappointing output in reality. The theory is structured as a set of overlapping themes, which are predominantly issues that practitioners see as causing pain and reward in collaborative situations. Five example themes are discussed: common aims; power; trust; membership structures; and, leadership. It is argued that the theory captures the complexity that underlies collaborative situations and conveys it in a way that seems real to those involved. It aims to empower those involved through legitimizing experienced frustration and providing conceptual handles to help address the practical issues involved.