This study's purpose is to examine the effectiveness of a promising intervention for emerging adults (EAs) with alcohol and other drug (AOD) abuse and justice involvement in achieving the ultimate outcome of reduced criminal activity. The study will also examine that effect on intermediate outcomes as follows: 1) reduced AOD use; 2) greater gainful activity (increased educational success, employment and housing stability; decreased antisocial peer involvement and relationship conflict); 3) and greater improvement in self-regulation (self-efficacy, goal directedness and responsibility taking). The intervention to be tested is Multisystemic Therapy-Emerging Adults (MST-EA). MST-EA is an adaptation of MST, a well-established, effective intervention for antisocial behavior in adolescents.