With funding from the U.S. Justice Department's National Institute of Justice (NIJ), SNL security experts have assessed the security features of several correctional facilities in Pennsylvania and Texas, as well as the blueprints for a Nebraska prison and a Michigan jail. SNL security experts examine the physical facility and obtain information about all areas of prison life. The security assessment is conducted from a systems perspective that includes input from the prison staff's knowledge of the facility. This article focuses on the SNL assessments of Pennsylvania correctional facilities. In its assessment, the SNL team pointed out security weaknesses prison officials had not considered; for example, one facility had a secure exercise yard located next to a wall with a doorway. The door had not been used for years, and it was not adequately secured. Recommendations were also offered on perimeter intrusion detection and the use of cameras and lights. At one Pennsylvania facility, the SNL team recommended that trees be cut along a fenceline and that one guard post be staffed full-time instead of only at night. This is a pilot program intended to refine the methodology of vulnerability analysis, so the methodology can be taught to correctional personnel.