Earthworm is an important factor to influence the physical feature of soil and microbial activities. Soil organic matter is a key factor for sustainable soil fertility. A good combination of soil components: earthworms, physical factors, chemical factors and microbial factors are essential for sustainability of soil fertility and environment. Bangladesh is a natural resource enriched promising delta. The weather and climate, geographical settings and environment have added more opportunity for the biodiversity as a harboring point. Recently there has been considerable interest in using numerous earthworm species to reclaim agricultural soils, to accelerate the decay of noxious organic wastes by producing composts for providing the organic manure to the soil. Since the presence of earthworm and biological activities of earthworm correlate with the fertility status of soil and environment, the study of earthworm diversity and availing the advantages from earthworms in various sectors is very important. Earthworm diversity, systematic account, abundance, distribution, soil nutrient, soil fertility are contents of this book.