Harvest is a major expense in hay production that could be reduced if a one cut hay system was developed. Soybean is a potential forage crop for the West with high protein and, due to its growth habit, would work best in a one-cut system. Irrigated soybean grain variety trials have been conducted in Idaho, Oregon and Washington in recent years with yields similar to Midwest irrigated areas. Very little is known about soybean forage production in the West. The objective of this study was to determine the effect of soybean maturity group and harvest date on yield and quality. Soybean was planted at 140,000 seeds/acre on May 15, 2012 at the Othello Research Farm near Othello, WA and the Utah State University Greenville Farm near Logan, UT. Varieties tested included: Asgrow 1431 [Maturity group (MG) 1.4], Asgrow 4531 (MG 4.5), Eagle Seeds Large Lad (MG 7), and Eagle Seeds Big Fellow (MG 7). Harvests occurred September 4th, 14th, 27th at Othello, WA and August 30, September 13, and 27th at Logan, UT. At Othello, forage yields increased with later harvesting and averaged 3.9, 4.7, and 5.6 dry tons per acre. Yields between varieties were not significantly different. Averaged over timing of harvest timings dry matter yields in tons/a were: Asgrow 1431 4.91, Big Fellow 4.88, Asgrow 4531 4.80, and Large Lad 4.45. On September 27th, maturity of the soybeans ranged from just flowering (growth stage R2) for Large Lad and Big Fellow to full seed development and leaves beginning to drop (growth stage R5) for Asgrow 1431 growth stage R5, with Asgrow 4531 between at growth stage R3. On September 27th the forage percent moisture content was 65.5, 77.4, 76.4, and 75.2 for Asgrow 1431, Asgrow 4531, Large Lad and Big Fellow, respectively. The maturity of the soybean varieties at Logan, UT, exceeded that in Othello and was: Asgrow 1431 growth stage R8, Asgrow 4531 growth stage R6, Large Ladd R3, and Big Fellow R4. Asgrow 1431 had peak dry matter 3.0 tons/acre at the earliest harvest. The other varieties continued to increase dry matter until the last harvest. On September 27th forage harvest moisture content was 41.4, 68.2, 70.3, and 68.0 for Asgrow 1431, Asgrow 4531, Large Lad and Big Fellow, respectively. Averaged over the harvest timings, dry matter forage production for Large Lad and Asgrow 4531 was greater than Big Fellow and Asgrow 1431 with yields of 5.2, 5.1, 4.7 and 2.6, tons/acre, respectively. Further research needs to occur to determine the quality and feasibility of drying hay with yields which reached as high as 6.3 tons with Large Lad in Utah and 6.0 tons per acre with Asgrow 1431 at Othello, WA.