Little is known about how ecological context influences the probability of transitions in the extent of pollinator specialization. One unexplored hypothesis suggests that transitions to environments with different light conditions should be accompanied by transitions in pollinator guild because of the combined effects of exposure to a new pollinator community and the different relative costs associated with pollinator attraction in the understory and the canopy. Using data from literature surveys, we compiled a data set of habitat light availability (e.g., canopy vs. understory), pollinator identity, and guild size for 481 angiosperm species representing four broad regions (India, Neotropics, paleotropics, and Canada). Phylogenetic independent contrasts were used to assess the degree to which transitions in canopy position are associated with transitions in the usage of particular pollinators and pollinator guild size. We further examined the degree to which each of these traits tends to be evolutionarily labile versus evolutionarily conserved. Our analysis demonstrates that species that tend to occupy the same position in the canopy are more closely related than expected by chance, as are species that follow traditional pollinator syndromes (e.g., bee or bird), but species that have exceptionally wide pollinator guilds (e.g., are visited by bees, flies, and moths) are widely scattered across the angiosperm phylogeny. Transitions to generalist pollination appeared to be strongly associated with beetle and fly pollination and with position in the canopy above the forest floor.