We investigated effects of selected physical factors on the catch rate of white crappie (Pomoxis annularis) in trap nets in Mississippi lakes. Population data were collected on 7,782 white crappie from 557 trap-net samples in the fall (N = 4,679 fish/243 nets) and spring (N = 3,103 fish/314 nets), 1987-1989. Generally, catch/day (N fish/24 hours) estimates were higher and less variable in trap nets set at water depths of 1.0-2.9 m and on bottom slopes of 0.0%-7.9%. Catch/day estimates were higher, but equally variable, in trap nets set perpendicular to the shoreline and at water temperatures of 16.0-19.9 C in the fall and 20.0-23.9 C in the spring. These findings indicate trap-netting efficacy could be augmented by sampling under the specified ranges of sampling conditions.