The traditional crop rotation in the semi-arid region of western South Dakota was winter wheat-fallow. The fallow phase was used to store soil water for the subsequent winter wheat crop. Widespread adopting of reduced-tillage systems in the region has increased water storage efficiency and this has allowed for the transition from the traditional rotation to intensified and diversified no-till cropping systems. A long-term rotation study was established in 1994 to compare the traditional winter wheat-fallow to no-till, diversified rotations. Nine rotations, two to six years in duration, are currently being evaluated. All phases of each rotation are grown each year. Reduced and no-till production practices are used to grow the crops except in the winter wheat–fallow rotation. Over the last 10 years, winter wheat yield in the conventional winter wheat-fallow rotation has averaged 3,292 kg ha^-1 while winter wheat in diversified rotations that include broadleaf crops (winter wheat-safflower-millet) or corn (winter wheat-corn-millet) averaged 2,552 kg ha^-1. Over the same time period, winter wheat in the winter wheat-millet rotation averaged 2,150 kg ha^-1. Yields of alternate crops including sunflower, safflower, chickpea and corn varied widely, and were strongly influenced by growing season precipitation.