Statement of the problem. It is a truism to point out that in all arguments there are two sides. One cannot identify these sides, much less support one against the other, without an understanding of the background of the argument. It is the purpose of this thesis to supply some background on the development of California's water law and on the Fallbrook water rights dispute so that the reader may better understand the issues in this controversy over which the federal government has received so much unfavorable attention in the nation's press. To do this the paper has been divided into five chapters. Chapter one introduces the problem. Chapter two presents the historical Spanish and Mexican view of water rights. Chapter three follows the development of California water law from the early mining period through irrigation and the use of subterranean supplies. Chapter four discusses the Fallbrook case in some detail, its status today, its coverage in the press and periodicals, and some of the questions which it poses. Chapter five concludes the thesis and states opinions which have been derived from the study.