Terrestrial isopods (Crustacea: Oniscidea) are important detritivores in many ecosystems. Because reproductive success and population dynamics of the Oniscidea depend on diverse biotic and abiotic environmental factors, the effects of global climate change on their biology may be significant. Although few studies have examined the relationship between climate change and population ecology in terrestrial isopods, much is known about their environment, genetics, physiology, behavior, life history, population biology, and evolutionary patterns. This review addresses the influence of biotic and abiotic environmental factors on terrestrial isopod reproduction. Significant biotic factors include microorganism-mediated sex determination, mate choice, sperm competition, maternal effects, food availability, and predation. Significant abiotic factors include temperature and moisture regimes, photoperiod, altitude, latitude, and microhabitat diversity. Studies of these factors reveal general patterns, as well as informative exceptions, in the ways different oniscid species, as well as different populations within a species, respond to environmental variation.