Grain production is a complex phenomenon, entailing several contributing factors. These factors influence grain production both directly and indirectly and the breeder is naturally interested in investigating the extent and type of association of such traits. Towards a clear understanding of the type of association, correlation, path and divergence analysis are logical steps. Studies like heritability estimates could also be helpful to know the performance of parents in hybrids. Similarly, Knowledge on the extent and the pattern of genetic variability present in a population is essential for further improvement of any crop. At present, there is lack of detailed information pertaining to these aspects. Therefore, this book intends to show comprehensive logical steps that a plant scientist should follow to reach a concrete conclusion on the variability and genetic relation of different characters taking an experiment conducted in bread wheat as an example. The book is important for plant breeders and other plant scientists interested in learning more about the ways of crop improvement.