Terrestrial mollusks are poorly known worldwide. The country has 183 reported species, 30% endemic and 7% are probably extinct. About 400 species are expected to inhabit the country. Biology, ecology, distribution, genetics and other areas of research are unknown for more than 95% of the species. The most diverse families are Spiraxidae, Orthalicidae and Subulinidae. However, the family that may have more species is Euconulidae. Euconulids inhabit the highlands, where less work has been done. The study of species of highlands will also rise the endemism rate. Future taxonomic, biological and ecological work should consider their low vagility, tendency to produce new taxa in sympatry, specific microhabitat requirements, hermaphroditism, high evolutionary rate (10% per million years), and divergence between species (2 to 30%). Urgent studies to protect the Costa Rican malacofauna include: distribution, abundance, effect of land use and climate changes on populations.