The night operations program is concerned with problems in optimizing human performance in relation to night vision devices and related sensors. To further this research, experimentation has been directed toward enhancement of the performance of the combat soldier in night operations. The report describes an experimental evaluation or four passive night vision devices, and presents results of the assessment of operator performance with these devices in target detection and search tasks. Subjects were required to detect targets (soldiers or aggressor type silhouettes) presented in two modes. Responses were recorded electronically. Data obtained were analyzed to determine performance effectiveness with the two subject devices and the effects were studied of illumination (starlight, half moon, full moon), distance (50 - 300 meters), target mode (moving vs stationary), target exposure time (10, 20, 30 and 90 seconds), and their interactions on search performance.