As part of a statewide regulation change in 1990, Texas Parks and Wildlife Department adopted 254-mm minimum length and 25-fish daily bag limits on crappies (Pomoxis spp.) at Sam Rayburn Reservoir. The objective of the regulation was to increase the size of harvested crappies while maintaining pre-regulation catch rates, harvest rates, and yield. Population and fishery parameters during 3-year unregulated and 8-year regulated periods were compared. Results indicated that mean length and weight of harvested crappies increased significantly (16% and 40%, respectively), while yield was maintained. Significant increases in trap net catch rates of crappies, coupled with a 36% increase in angler catch rates, suggested an increase in stock-length crappie abundance during the regulation period. However, similar increases in trap net catch rates at nearby Toledo Bend Reservoir (regulated with a bag limit only) may indicate that the increase in crappie relative abundance at Sam Rayburn Reservoir was not directly associated with the regulation. Harvest rates, both number and weight per hour, did not change significantly between pre- and post-regulation periods. At Toledo Bend Reservoir, harvest as well as effort levels oscillated over annual periods according to the supply of young, available crappies, suggesting a pattern of growth overfishing. Growth rates remained above average indicating the accumulation of protected-length crappies did not affect growth. Although the 25-fish bag limit was incorporated as part of the crappie regulations at Sam Rayburn Reservoir, it was not biologically effective. Application of the appropriate harvest restrictions should be reservoir-specific, based not only on environmental and biological characteristics, but the preferences of the angling clientele.