Disclosed herein are herbicidal compositions comprising a synergistically herbicidal effective amount of (a) penoxsulam, or an agriculturally acceptable salt thereof, and (b) mefenacet, or an agriculturally acceptable salt thereof. Also disclosed herein are methods of controlling undesirable vegetation in rice, which comprise applying to vegetation or an area adjacent the vegetation or applying to soil or water to prevent the emergence or growth of vegetation (a) penoxsulam, or an agriculturally acceptable salt thereof, and (b) mefenacet, or an agriculturally acceptable salt thereof, wherein (a) and (b) are each added in an amount sufficient to produce a synergistic herbicidal effect.