The Massachusetts Youth Screening Instrument–Version 2 (MAYSI-2) is a brief screening tool used to identify youth in the juvenile justice system who are at-risk of mental-health-related difficulties. The MAYSI-2 was administered to 5,205 African American and Latino/a youth throughout Chicago, Illinois, who were on probation and residing in the community. This study investigated differences (i.e., legal status, gender, age, race/ethnicity) in reporting of mental health symptoms and substance use on the MAYSI-2. Females scored above the clinical cutoffs more frequently than males, and there were few differences found between diverted and adjudicated youth. Age comparisons revealed mixed results. Overall, youth in the current sample scored above the clinical cutoffs less often than youth in the MAYSI-2 norm reference groups. Nonetheless, during the first phase of this study, the MAYSI-2 demonstrated effectiveness by accurately identifying a substantial portion of youth in need of mental health and/or substance abuse treatment.