All the important diaries are presented, with two exceptions. One is Argüello's account of his expedition to the upper Sacramento and Trinity rivers in 1821. This manuscript is now being translated and annotated as a separate work by Professor Robert F. Heizer, of the University of California, and Professor Donald C. Cutter, of the University of Southern California. The other is the Estudillo expedition to the southern San Joaquin Valley in 1818. The Estudillo documents have already been translated and edited by Dr. Anna H. Gayton (1936) and can readily be obtained. In addition to the well-known, formal reports to the Central Authority I have translated several excerpts from letters and memoirs. The contemporary correspondence occasionally discusses briefly or extensively expeditions of interest concerning which we have no other knowledge. For completeness, therefore, these accounts must be included. Concerning the memoirs some reservation is necessary. This type of document furnishes a great deal of material for the later period of 1820-1840. There are, however, a number of passages which refer quite clearly to events in the preceding decade. These are the reminiscences of old men, talking about campaigns and battles which occurred more than half a century earlier. The raconteurs were mostly rather ignorant, their memory faulty, their attitude boastful. Their command of fact is definitely unreliable, their personal viewpoint highly colored and biased. Their accounts are nevertheless valuable for the picture they give of the day-to-day personal contact between the white men and the natives, and for the many interesting sidelights on the life and the land of the Central Valley in its original condition. The author wishes to acknowledge with thanks a grant made by the Institute of Social Sciences, of the University of California, for photocopying and clerical assistance. I. EARLY EXPEDITIONS, 1776-1803 During the initial period of settlement and exploration in California, from 1769 to 1776, several important and well-known expeditions entered the area, among them those of Portola, Anza, Fages, and Cañizares. As a result the coastal strip and the vicinity of San Francisco Bay became well known. The interior did not receive so much attention. Following Anza only two recorded expeditions went into the Central Valley, that of Moraga, described by Palóu (Bolton, 1926) and that of Fages, the account of which has been translated by Priestley (1913).