Abstract: Quinolinone compounds of the formula ##STR1## in which R.sup.3 is H, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, alkoxyalkyl, alkoxyalkoxyalkyl, cycloalkyl, alkylthioalkyl, aralkyl, cyanoalkyl, alkoxycarbonylalkyl, hydroxy, or alkoxy; X is H, halogen, alkyl or haloalkyl; Y is H, halogen, alkyl, haloalkyl, alkoxycarbonyl, cyano, or nitro; Z is H, halogen, alkyl, haloalkyl, alkoxy, alkenyl, alkynyl, haloalkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, alkoxycarbonyl, cyano, or nitro; R.sup.1 alkyl, alkenyl, alkynyl, haloalkyl alkoxyalkyl, or haloalkoxyalkyl; and R.sup.2 is H, alkyl, haloalkyl, alkoxy, haloalkoxy, alkylthio, alkylsulfinyl, alkyl, alkoxy, halolkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, or halogen; and the corresponding 3,4-dihydroquinolinone compounds as herbicides.