Early planting, narrow row spacing, reduced seeding rates, and careful variety selection are production practices that producers in Iowa have been encouraged to adopt to increase soybean [Glycines Max (L.) Merr.] seed yield. There is a large industry demand for protein and oil derived from soybean and the response of seed composition to high-yield systems should be evaluated. Four separate studies were established at three locations in Iowa between 2004 and 2006. Treatments were soil fumigation, planting date, row spacing, seeding rate, and varieties in various combinations depending on the study. Year and location mediated the rate of increase or decrease to changes in planting date, seeding rate, and variety. Protein and oil concentrations ranged from 338 to 376 and 179 to 205 g kg^-1 for 23 varieties, respectively. Protein content increased 97.5 g kg^-1 and oil content decreased 90 g kg^-1 as planting was delayed from late April to early June. As seeding rate increased from 185 000 to 556 000 seeds ha^-1 protein increased 40 g kg^-1 while oil decreased 8.5 g kg^-1. Row spacing had no effect on protein or oil content. Early planting and narrow row spacing significantly increased yield; therefore, protein and oil production ha^-1 was maximized in these conditions, regardless of specific seed concentration changes. Total protein and oil output per area are determined by seed yield. Therefore, high-yield production practices should be adopted despite seed composition changes.