Objective: To examine associations between the Massachusetts Youth Screening Instrument-Second Version (MAYSI-2) and Diagnostic Interview Schedule for Children-Present State Voice Version (DISC-IV) and the extent to which they overlap in identifying youths with mental health concerns. Method: Among 325 New Jersey and South Carolina correctional youths, associations were examined using receiver operating characteristic analyses and logistic regression (binomial and multinomial). Results: MAYSI-2 subscales generally mapped best onto homotypic DISC-IV disorders; however, many subscales mapped almost as well onto heterotypic disorders. Alcohol/Drug Use and Suicide Ideation, respectively, identified youths reporting substance disorder and recent attempt; other subscales did not identify parallel DISC-IV disorders as well. Conclusions: MAYSI-2 identifies some DISC-IV disorders better than others. Lack of overlap may result from MAYSI-2's combining diagnostic constructs into single subscales. Substantial percentages of disordered youths were not identified by corresponding subscales. In systems with multiple avenues of referral, the MAYSI-2 is a useful intake screen, but its utility as the sole means for identifying diagnoses for treatment purposes is limited. The authors differentiate between screening for emergent risk and service needs, recommending best practices for a comprehensive approach to mental health assessment among justice youth.