Pinus monticola Sj seedling mortality, timing and extent of fruitir^, strobilus attrition, crossing success, seed yield, and seed weight are compared for 18 Sj lines and their outcrossed half-sib lines. No reproductive barriers are restrictive enough to preclude continued inbreeding. Filled seed yields from second generation inbreeding are low but consistent and large enough to justify continuing an experimental program. Results of experimental single crossing between Sj lines should guide decision on a practical inbreeding program. LITERATURE REVIEW An extensive literature deals with effects of first-generation selfing in conifers, especially Pinus. The summary by Franklin [1970) covers much of this literature through 1967, and adequately describes effects of inbreeding as reflected in S;^cone and seed yields, seed germination, and mortality and early growth of seedlings. His table 3 sums up these effects in Pinus, pointing out that in general, and in comparison to outcrossing, neither cone yield nor total (filled plus hollow) seed yield are affected, filled seed yield is reduced about one-third, hollow seed yield is increased about 2-1/2 times, seed germination is reduced about one-tenth, seed weight is little affected, seedling mortality is about one-third higher, and seedling height is reduced about one-fourth. These general conclusions are quite applicable to western white pine, except that in young trees (18 to 21 years) cone yield may be reduced, if not in the older trees (30 to 50 years) covered by Franklin. Several times in the past (Bingham and Squillace 1955; Squillace and Bingham 1958; Barnes and others 1962) we have noted the wide variation in self-fertility of different western white pine mother trees. Some trees are comparatively self-fertile, others self-sterile, in respect to seed yield, as is shown in table 1. The self-fertile trees like parent 58 are equal or better in filled S^seed yield and give somewhat greater hollow seed yield. The seat, manner of operation, and timing of the incompatibility mechanisms are unknown, but the effect is strongly associated with the mother tree.