Pea (Pisum sativum L.) has been used to replace fallow and to sustain dryland crop yields in arid and semiarid regions, but information to optimize its management is required. We evaluated pea growth, yield, and water use in response to tillage, crop rotation, and weed management practice from 2005 to 2010 in the northern Great Plains, United States. Tillage systems were no-tillage and conventional tillage, and crop rotations were spring wheat (Triticum aestivum L.)–pea (W-P), spring wheat–forage barley (Hordeum vulgaris L.)–pea (W-B-P), and spring wheat–forage barley–corn (Zea mays L.)–pea (W-B-C-P). Weed managements were traditional (conventional seeding rates, early planting, broadcast N fertilization, and reduced stubble height) and improved (variable seeding rates, delayed planting, banded N fertilization, and increased stubble height) practices. Pea plant stand, height, pod number, grain and biomass yields, and water-use efficiency (WUE) were 4 to 23% greater with the improved than the traditional weed management practice, but seed number per pod was 5% greater with the traditional practice. Plant height, pod number, biomass and grain yields, preplant and postharvest soil water contents, and WUE were 2 to 51% greater with W-B-P and W-B-C-P than W-P. Pea yield and WUE increased with extended crop rotation with nonlegumes and the improved weed management due to enhanced plant growth and seed characteristics as a result of greater soil water availability, seeding rate, and wheat stubble height. Dryland pea yield and water use can be enhanced by using extended diversified crop rotations and by increasing seeding rate and wheat stubble height.