Students and researchers in plant breeding and molecular applications, and those interested in innovative biological research realized the need for comprehensive knowledge in Quantitative Genetics. Software packages have also grown concomitantly providing ready-made path to analysis of data generated. But users feel despondent as their knowledge is deficient to understand the logic or process steps in such software. They want more knowledge in Quantitative Genetics and seek quality books. This book aims to answer those needs. Its organization and coverage of content differ from the pattern in well-known books on the subject. The book is unique in its effort to carry along readers with no specific mathematical/ statistical background, especially those who specialize in Agriculture, Biology and related fields, to a high level of quality experimentation employing quantitative genetic tools. With an introduction explaining how contemporary developments in the fields of genetics, statistics and particularly probability theory blended to evolve the subject of quantitative genetics, the book provides practical details of probability distributions and their application in genetic investigations. Specifically designed plant breeding experiments are used to explain and interpret various mating designs and their specific utility. In the process, definition of additive effect and additive genetic variance are defined anew and the fallacy in their formulation found in illustrious treatises by Mather, Jinks and Falconer is corrected. In analyzing genetic variation, Fisher’s average excess and effect of gene substitution are used probably for the first time in a book.