Little information is available on the breeding systems of tropical forest trees. Yet a knowledge of reproductive methods is essential for an understanding of the patterns of gene flow and genetic differentiation within and between populations. Such information, in turn, is fundamental to an understanding of speciation and the genetic relationships between species. This paper reports the results of a study on the breeding systems of tree species of a lowland tropical community. The main objective was to determine the relative proportions of self-compatible and selfincompatible species in the community. Controlled pollinations were performed to test for self-compatibility. Supplementary data in the form of observations on floral biology were collected to determine the frequency of dioecious, monoecious, and dichogamous species.