The response of irrigated spring barley (Hordeum vulgare L. ‘Steptoe’) to broadleaf herbicides applied at three growth stages was studied at Torrington, WY, in 1984 and 1985. Dicamba (3,6-dichloro-2-methoxybenzoic acid), dicamba plus 2,4-D [(2,4-dichlorophenoxy)acetic acid], and dicamba plus MCPA [(4-chloro-2-methylphenoxy)acetic acid] visibly injured barley when applied at all growth stages. These same treatments reduced barley height when applied at the 2- to 4-leaf and fully tillered stages. Yield differences among treatments were not significant. However, kernels/spike and kernel weight were reduced by dicamba or dicamba plus MCPA when applied at the fully tillered or boot stages, and test weight was reduced when dicamba was applied at all growth stages. Seed protein content did not differ in 1984. However, several herbicide treatments increased seed protein in 1985, especially when applied at the boot stage. Proline or lysine content did not differ among treatments.