Integration of distributed generators in distribution system plays major role in the planning of electric power distribution systems. While planning an engineer must look after the technical as well as economical benefits of the DG integration. Optimization is one good approach to achieve the best possible benefits from the integration of DGs in short time. In this book, optimal allocation of distributed generators in radial distribution systems using well established optimization algorithms is discussed. It includes mathematical modelling, single objective optimization, multi-objective optimization, various distribution system load models and voltage stability analysis. I hope this book is most useful for researchers and masters level students in electrical power distribution systems area.