Methods used in the development and testing of stand models for Douglas fir and lodgepole pine are described briefly. Influence of spacings from 3.3 to 19.8 feet on number of trees per acre, basal area per acre, and average d.b.h. is shown graphically for Douglas fir. The importance of knowing distribution as well as amount of mortality is stressed and illustrated. Use of the model for studying thinning is described.Study of a lodgepole pine model, which also includes tree height and volume per acre, suggests that the general approach based on crown width and d.b.h. of open-grown trees could be applied to other species. Because of the ease and speed of manipulation of these models they could become an important operational and research technique.