Bottom trawl samples showed that there were diel changes in bluegill abundance in limnetic areas of Lake Wingra, Wisconsin, from April to November 1970. Catches during daylight were greater than those at night. Sampling both littoral and limnetic habitats during September, when diel migrations appeared most dramatic, indicated that fish moved onshore after sunset and offshore after sunrise. All size classes sampled appeared to participate in these movements. Larger fish predominated in littoral areas, suggesting either longer residence time during a did cycle or a proportionately larger resident population. Stomach analyses indicated that bluegills ate mostly zooplankton in limnetic areas, whereas macrofood organisms such as insects dominated the prey of littoral zone fish. Quantitative comparisons of stomach content demonstrated that smaller fish benefited most from the offshore migration.