A cooperative experiment begun in 1980 was designed to evaluate the productivity and other characteristics of 16 spur and 12 standard strains of `Delicious' apple on two rootstocks (M.7 EMLA and MM.111 EMLA). All trees were propagated at one nursery, and plantings were established in Michigan, Washington, Oregon, Idaho, Indiana, and British Columbia. In Michigan, trees of standard strains were consistently larger than trees of spur strains 8 years after planting. Early yields were greater on M.7 EMLA than on MM.111 EMLA, but trees were more subject to leaning under heavy crops on M.7 EMLA. In general, spur-type strains yielded more fruit per unit trunk cross-sectional area than standard strains. Yield was more closely associated with fruit-setting ability than with flower density, and fruit size declined as fruit set increased. Length/diameter ratios and biennial bearing indices also differed significantly among strains.