e seek to determine the factors which control the success of lianas across macroecological gradients. Lianas have a strong impact on the growth mortality and biomass of tropical trees and are reported to be increasing in dominance so understanding their behaviour is important from the perspectives of both ecological and global change. Location Lowland and montane Neotropical forests. Methods Using 65 standardized samples of lianas (>= 2.5 cm diameter) from across the Neotropics we attempted to account for characteristics of both the environment and the forest in explaining macroecological variation in liana success in Neotropical forests using regression analyses and structural equation modelling. Results We found that both liana density and basal area were unrelated to mean annual precipitation dry season length or soil variables except for a weak effect of mean annual precipitation on liana basal area. Structural characteristics of the forest explained more of the variation in liana density and basal area than the physical environment. More disturbed forests generally tended to have a higher liana density. Liana basal area however was highest in undisturbed forests. Main conclusions The availability of host trees and their characteristics may be more important than the direct effects of the physical environment in controlling the success of lianas in Neotropical forests. Changes to the tropical climate in the coming century may not strongly affect lianas directly but could have very substantial indirect effects via changes in tree community structure and dynamics.