The problem has recently been reopened by S. F. Cook. In 1943 he published an evaluation of Kroeber's estimates, based on essentially the same data, and the result was to increase the estimate by about 10 per cent. In the last two years Cook has begun a more intensive investigation, the results thus far being new estimates for the San Joaquin Valley (1955) and for the Northern California coast (1956). The upshot of these last papers has been to double Kroeber's estimates in the areas under consideration. The basis of the new estimate suggested by Cook is a more intensive use of historical sources and readier acceptance of the observations found there. He says, "Evidence of misstatement should be looked for and, if found, should be discounted or discredited. Otherwise it should be admitted at face value." Kroeber has recognized the discrepancy between his estimates and those based on historical statements. He agrees that, if the extrapolations from the latter are accepted, the Merriam figure of 260,000 persons would probably be more accurate. The difficulty there is that "if we accept 260,000, one-quarter of all United States Indians were in California; and this seems unlikely enough. Shall we then assume that Mooney and practically all American anthropologists computed far too low?" (1939, p. 179). Kroeber leaves the question unanswered but Cook's recent work carries the implication that the answer is decidedly affirmative. The estimate in this paper of the population of the California Athabascans agrees with Cook's results, raising Kroeber's estimates; in fact, it goes even further than Cook in that direction. But the estimates here, with one exception, have been based on village counts by ethnographers rather than on historical data. The fact that the estimates run so high tends to bear out Cook's contention that the Kroeber estimates should be raised. In basing population estimates on village counts there are several sources of error. Among these are assumptions regarding the number of persons per house and the number of houses per village. I believe that all the assumptions I have made in this regard have been conservative and therefore would not result in overestimates. The number of houses per village can sometimes be calculated rather closely from the number of house pits seen in the sites. That is, the houses can be calculated closely if the assumption is correct that four-fifths of the number of house pits in a site represents the number of simultaneously occupied houses. Admittedly, this figure is rather speculative, but the best opinions I have been able to get grant that it is probably conservative.