Rice is the staple food for over half the world's population, and is the globe's most popular food that shapes religious festivals, customs, cuisine and celebrations. Even though rice needs assured irrigation to complete its life cycle, about 45 per cent of the global rice area is under rainfed cultivation, which frequently undergoes drought situation. To improve adaptability of the crop under rainfed ecosystem, heterosis breeding for drought associated traits utilizing diverse germplasm is one of the best methods to improve genetic background of the crop. Diallel mating method helps to find out the best combiner parents utilizing combination of crosses among all inbred lines. This book blends information on the mating design and combining ability studies to identify superior parents and cross combinations for heterosis or pedigree method of breeding. Experimenting Diallel mating design using different physiological and agronomical drought associated traits are well explained in this book. This study and methodologies involved in it can be very useful to plant scientists and breeders in formulating and implementing breeding programmes for drought tolerance.