Recent studies have demonstrated the increasingly important role of lianas (woody vines) in forest regeneration species diversity and ecosystem-level processes particularly in the tropics. Mechanisms responsible for the maintenance of liana species diversity could yield new insights into the maintenance of overall species diversity. Lianas contribute to forest regeneration and competition not only by competing directly with trees but also by differentially affecting tree species and thus changing how trees compete among themselves. In addition they contribute considerably to ecosystem-level processes such as whole-forest transpiration and carbon sequestration. As the rate of tropical forest disturbance increases they are likely to increase in relative abundance throughout the tropics and the importance of lianas to many aspects of forest dynamics will grow.