This NIJ Fact Sheet, developed by the National Law Enforcement and Corrections Technology Center (NLECTC), presents introductory information on portal contraband detection technology. This technology is used to detect contraband being smuggled into prisons and jails by corrections staff, inmates, and visitors who must pass through access/egress points to enter and leave the facilities. Several types of devices are used at these portal or access/egress points and are discussed in this Fact Sheet. These include metal detectors, millimeter wave detection devices, magnetometer (gradiometer) metal detection, electric field tomography, heartbeat detection, ion scan technology, and backscatter x-ray contraband detection. These devices are used at access/egress points to detect the presence of different types of contraband such as nonmetallic weapons, drugs, tobacco, and wireless communication devices. The successful use of these devices usually occurs in conjunction with other security functions. These additional functions include verification of incoming and outgoing staff, and inmate identification; body searches of staff and inmates where appropriate; manual and x-ray search of briefcases, handbags, and lunch containers; and removal of metallic items, including shoes, to accommodate metal detector searches. Additionally, criteria for developing new technologies for this area are discussed.