Offenders who require similar levels of security can be vastly different in other important ways. Conversely, offenders of very different risk levels may share similar traits or service needs. Thus, each offender has a unique profile. Assessing health, mental health status, and victimization potential is a high priority for most classification programs. Educational and vocational concerns are also prominent. Less traditional factors being assessed include substance abuse, relationship skills, and family interactions. The medical, curative model for needs assessment and treatment is attractive but, by itself, usually inadequate. The role of the correctional environment in influencing offender behavior is becoming increasingly understood. Needs assessment also faces several types of barriers: limits of the person-centered approach, lack of meaningful programs to which to assign offenders, and program instability due to frequent inmate transfers.