Benson Ginsburg's early studies of canid socialization and wolf social and reproductive behavior were focused, in part, on the degree to which there was flexibility in social development and specifically whether there was a critical period during development after which wolf pups could not be socialized to humans. My focus was the degree to which differences in canid ecology and social structure were correlated with differences in the plasticity of social and reproductive behavior, including development. Canid species are unusual among the Mammalia in being primarily monogamous. Males may play an indirect or direct role in parental care, depending on a species degree of sociality. Canid species also differ in developmental parameters, and reproductive suppression is common in the group-living pack hunters. I review comparative studies of the social and reproductive behavior of three South American canids which vary in their degree of sociality and explore the degree to which the species are ecologically and socially flexible.