Disclosed herein are herbicidal compositions comprising a herbicidally effective amount of (a) a pyridine carboxylic acid herbicide or an agriculturally acceptable N-oxide, salt, or ester thereof, and (b) a photosystem II inhibitor, or an agriculturally acceptable salt or ester thereof. Also disclosed herein are methods of controlling undesirable vegetation 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) a pyridine carboxylic acid herbicide or an agriculturally acceptable N-oxide, salt, or ester thereof, and (b) a photosystem II inhibitor, or an agriculturally acceptable salt or ester thereof, wherein (a) and (b) are each added in an amount sufficient to provide a herbicidal effect.