The present research studies were conducted to determine the effects of water stress on various yield and yield associated traits of bread wheat. Nine newly evolved wheat genotypes (two mutant lines, 3 conventionally bred and one doubled-haploid line, 3 released high yielding varieties) were evaluated along with drought tolerant check varieties using various water stress levels under field conditions. The split plot experimental design was used with four treatments: T1: single irrigation was applied at seedling stage (stress induced during all other stages); T2: two irrigations were applied at seedling and anthesis stage (stress applied at tillering, booting, heading and grain filling); T3: three irrigations were applied at seedling stage, at booting stage and at milky stage (stress imposed at tillering and anthesis); and T4: (Control) where genotypes were given normal (six) irrigations. Water stress showed significant effects on various quantitative and physiological traits. Genotypes showed different response to various stresses. This book will comprehensively present the brief research studies conducted for improvement of water stress tolerance in wheat genotypes.