Laboratory studies on the biology of Australorbis glabratus, snail vector of Schistosoma mansoni, revealed that the period from hatching to laying may be as brief as 3 weeks. Allowing 8 to 9 days for incubation of eggs, the egg-to-egg cycle is potentially 1 month. In one experiment the mean diameter at maturity was 12.8 mm. The best growth rate, obtained with snails in continuously changing tap water, was 20 mm in 2 months. These results are believed to approach the biological potentials of A. glabratus—they are consistent with limited field observations on growth; they explain the profound capacity of the snail for repopulation after stress of natural conditions and mollusciciding; and they are pertinent to the epidemiology of the disease.