We investigated calling behavior and call structure for eight species of treefrogs in the genus Scinax, and document noteworthy patterns of interspecific variation that largely reflect habitat and social environment in this report. The five species in the S. ruber clade call in open areas or forest edges near standing water and produce simple calls at relatively high rates and low to moderate frequencies. Species from the S. catharinae clade call from more forested habitats and produce complex, higher frequency calls at relatively low rates. Differences in the range of activity temperatures and habitats among species reflect differences in geographical distribution and spatio-temporal selection of microhabitat during calling. In general, species with high calling rates also had high rates of locomotion during calling activity and were active at warmer temperatures. One exception was S. crospedospilus, which has an extremely high calling rate but exhibits among the lowest rates of locomotion and activity temperatures. Complex calls delivered at lower rates and simple calls produced at high rates represent extremes of the range of calling behavior among these species of Scinax.