Hawaii's ~750 species of endemic terrestrial and arboreal snails have experienced great extinction, among the most severely impacted being members of the subfamily Achatinellinae. Efforts over the last 30+ years to understand the causes of extinction, to monitor the survival of species, and to conserve what remains of this spectacular radiation (~100 spp. in 4 genera) include field-demographic studies of populations on four islands, monitoring a population of one species within a predator exclosure, captive propagation, and population-genetic studies. The O`ahu-endemic genus Achatinella has diminished from 41 species to about 9 at the present, 7 of them represented among the 1,500 achatinelline snails from three genera in the tree-snail laboratory. By monitoring climatic conditions in the field, we were able to establish 'climates' in environmental chambers that have encouraged population-growth demographics comparable to field populations for most species. For others, species that seemingly live in almost identical field situations, laboratory propagation is far less successful. Sample data for lab populations include original (field-collected) vs. current numbers as follows: A. fuscobasis, 11/440; A. decipiens, 12/38; A. lila, 4/296; and A. apexfulva, 14/12. Molecular genetic studies have been used to guide conservation efforts, in the field and the laboratory, for A. mustelina, a model that will be used for other species as well.