Use of earthworm species to biodegrade various substrates (industrial wastes, agricultural residues, etc.) for composting has proven to be successful after initial stabilization of vermi beds. This study presents optimization of vermi beds (soil + cowdung) for culturing of earthworms (Eisenia fetida, Eudrilus eugeniae, and Megascolex megascolex.). Optimum proportion of soil + cowdung (1:3) for culturing of earthworms has shown highest number of earthworms hand sorted in all the three species. Among three species, E. eugeniae showed highest number of earthworms after 32 days. In compost preparation, earthworms reduced pH as follows: E. fetida, 6.7 to 6.1; E.eugeniae, 6.7 to 6.0; and M. megascolex, 6.7 to 6.4.