Spiderlings of the theraphosid spider Hysterocrates gigas were reared for 12 weeks with a superabundance of prey solitarily and in groups of two and four to examine the influence of rearing group size on growth. This taxon was selected because observations made on captive populations indicate that Hysterocrates spp. tarantulas have an unusually high level of mutual tolerance and captive juveniles have been observed to feed cooperatively on large prey until several months old. Cannibalism was only observed in one instance, in a group of four. There was no significant effect of rearing group size on increase in body mass. There was a tendency for a greater asymmetry in final weight in dyads than in tetrads. No difference was found in the amount of time spent feeding by individuals between the different group sizes. Hence, benefits of group living in Hysterocrates gigas spiderlings were not evident in this study.