The diversification in form and function of flowers, the reproductive structures of angiosperms (flowering plants), provides some of the most compelling examples of adaptation by natural selection. Flowers vary enormously in size and display greater structural variation than the equivalent structures in any other group of organisms. This diversity provides outstanding opportunities for investigating the functional association between floral traits and plant mating. The recent integration of theoretical, comparative, and experimental approaches in evolutionary biology is giving rise to new insights into the relations between floral diversity and plant mating strategies.