TRainfall is the most uncertain and important production factor for dryland agriculture. Dryland agriculture in India is always a risky enterprise because of variability in seasonal monsoon rains. It is not uncommon to observe both inter and intra-seasonal drought in Indian scenario. The available scope to increase the productivity under dryland agriculture was not fully tapped because of dearth of information from agrometeorological side especially on risk free growing period, right from field preparation. Proper blending of climatic information with the crop management agronomy would be one among the best ways to increase and stabilise the production under dryland situation. The importance of length of growing period is witnessed particularly in dryland agriculture. Different agrometeorologists suggested different methods for the computation of LGP. In this book, authors briefly described about the three different models for computing LGP for dryland. This book will be useful for P. G students and research scholar.