Rhythmic bedding is a prominent feature of North American and European Upper Cretaceous pelagic carbonate sequences deposited in epicontinental and continental-edge settings. Such bedding rhythms can result from variations in carbonate productivity, terrigenous dilution, redox conditions, or bottom currents. Each type of bedding cycle is expressed differently in the stratigraphic record but probably was caused by climatic cycles that are linked to variations in the Earth's orbital characteristics (Milankovitch cycles). Thus, pelagic carbonates of Cretaceous age acted as particularly sensitive recorders of orbitally induced changes in climate. Documentation of these bedding rhythms will permit detailed chronostratigraphic and lithostratigraphic correlations and will further illuminate depositional processes in Upper Cretaceous carbonate sequences.