The study, which was conducted by the Girls Study Group established by the U.S. Justice Department's Office of Juvenile Justice and Delinquency Prevention (OJJDP), found that 73 of the 143 instruments reviewed showed favorable gender-based analysis or provided gender-based development. Seven instruments were assessed as "unclear" (produced mixed or inconsistent gender-based performance information); eight instruments were rated "unfavorable" (yielded negative gender-based performance information); and 55 instruments were rated as "unknown" (lacked gender information). Of the four categories of instruments reviewed - risk and risk/needs instruments, global needs assessment instruments, substance abuse instruments, and mental health instruments - the mental health instruments were most sensitive to gender concerns. Results for the risk assessment instruments were the least encouraging. This report advises that practitioners who want to assess girls' risks and treatment needs accurately face considerable barriers and unknowns. Local juvenile justice systems and community prevention programs should consider the following issues when selecting and administering instruments: the instrument's purpose, gender-based performance, strength-based instruments (emphasizes positive factors upon which to build development), local validation, and cost. This report provides a checklist of appropriate questions to ask when selecting risk and needs assessment instruments for girls. 8 notes and 4 references