The general anthropology and history of the California natives has been exhaustively studied, in particular their archaeology and ethnography. Much is also known concerning the vicissitudes of their existence since the coming of the white man. The mission experience has been thoroughly explored and is admirably documented. The period of the Mexican War and the gold rush has been the subject of hundreds of books and articles. Students interested in problems of human biology, ecology, and sociology centering on the indigenous population of California have readily available certain important sources of information. First, there is a wealth of archaeological data--materials deposited in museums, many archaeological sites which are in their original position, reports, and monographs. Second should be mentioned the long series of ethnographic investigations carried on by various agencies over half a century and based primarily upon the word of living informants. Third are the general historical and mission records, which display the relation between the Spanish-Mexican civilization and the native. These merge into the fourth source of knowledge, the official documents, letters, memoirs, diaries, and contemporary newspaper accounts which give us an exceedingly detailed picture of the Indian during the period of first exploitation by the Americans. The fifth category includes the documentary records since approximately 1855: the reports of the Indian Service and of Army Officers, correspondence of all sorts among Federal and State functionaries, and investigations by Congressional or Legislative Committees. These documents, most of which are to be found in libraries and public archives, bring the student down to the present time. In spite of this wide spectrum of source material there is one area which has been as yet relatively little explored but which merits attention on the part of those concerned with the human development of California. I refer to the contact between the Spanish-Mexican settlers and the aboriginal population, not through the medium of the missions but within the natural environment of the Indians. Over a period of more than fifty years, while converts were being drawn into the mission system, priests, soldiers, and ranchers were continually reaching out into the interior, opening up the country and thus impinging upon native life. A constant succession of expeditions, sorties, raids, and campaigns moved in from the coast, left their mark on the land and its inhabitants, then retreated to the missions and presidios. Most of these forays were undertaken without official sanction and left no record save in the memory of a few old men, who were interviewed by H. H. Bancroft many years after the event. A good many expeditions and military campaigns, however, were sponsored by the government or the church. Of these, diaries were kept and written reports made. A rather long series of such documents still exists.