The first experiment in thinning western white pine (Pinus monticola Dougl.) was planned and established by J. A. Larson and D. R. Brewster in 1914 in a 55-year-old stand on the Priest River Experimental Forest, Idaho. It was designed to compare the effects of three thinning treatments on volume and quality growth, and on total volume production with an unthinned stand. As thinnings of saw-log material in this species are becoming salable, it is desirable to know if production can be increased by this early stand treatment and, if so, to what extent.