Trap net samples of white crappie were collected in the spring from Rend Lake, Illinois, from 1978 through 1983. Analyses of age, growth, length-frequency, and diet reveal a dominant, slower-growing 1978 year class and two sub-populations, separated by growth rate and feeding behavior. At ages II–VI crappie feeding on fish have back-calculated total lengths 10.1, 27.6, 42.6, 58.9, and 63.2 mm greater than those of crappie of the same age feeding on an invertebrate diet.