Cotton is said to be a gift of the Indian sub-continent to human civilization. The key role that cotton plays in our economy can be gauged from the extent of area under the crop as well as trade, processing, manufacture, export of raw cotton and cotton textile goods. Cotton fibre is the only natural fibre that can clothe the world population. Cotton improvement can be ccomplished by favorable combination of genes in cotton varieties through hybridization. Heterosis breeding played a significant role in yield and quality improvement in desi cotton. This work explores the genetic behavior of these traits in old world cotton and will help cotton breeders to choose suitable parents for hybridization in their genetic improvement programs of cotton.This book / research findings may provide guidelines to the breeders for improving seed cotton yield and other quality characters in desi cotton by making selection of desirable plants.