This paper focuses on forms that involve multiple partners pooling some strategic decision rights and even some property rights while keeping distinct ownership over key assets, so that they require specific governance to monitor and discipline their interactions. I identify these arrangements as 'hybrid organisations', in line with the terminology proposed by Oliver Williamson (1996). In the second section I go farther in identifying and delineating these arrangements. The third section discusses the forces at work that may explain why parties accept to share strategic rights. The fourth section exhibits different mechanisms of coordination that may play distinctly or in combination. The fifth section suggests a typology of hybrid organisations based on the prevalence of each different mechanism. The final section concludes by emphasising problems raised by the very existence of hybrids, particularly with respect to competition policies.