Among 21 species for which information is available (out of ca. 100 extant species), three diploglossines, five gerrhonotines, and six anguines attend their eggs during incubation, implying that parental behavior might be synapomorphic for the more inclusive clade Anguidae. A captive Gerrhonotus infernalis attended her clutch for 62 days, occasionally left it to feed and defecate, and did not pursue prey in the presence of her neonates. Viviparous Barisia imbricata, Elgaria coerulea, and Mesaspis moreleti consume extraembryonic debris and sometimes assist with birth; viviparous M. monticolus and Diploglossus fasciatus (mode of reproduction unknown) likely attend their neonates; and parental behavior is perhaps absent in viviparous Anguis fragilis and Ophiodes. Meager circumstantial evidence suggests that chemical cues influence those activities in anguids, and that thermoregulation, defense of eggs and/or young, and hygienic removal of spoiled eggs or birth debris are among the ecological advantages of their parental behavior. Viviparity has evolved at least four times within Anguidae, consistent with theoretical expectations that live birth is favored in egg-guarding taxa. These diverse lizards thus show much promise for studies of specialized parental investment in ectothermic vertebrates.