Most of the conodont data presented in this report (table 1) were acquired to support 1:100,000-scale geologic mapping of the Winchester 30' X 60' quadrangle by the U.S. Geological Survey (USGS). Conodonts were chosen to provide a biostratigraphic framework for the Upper Cambrian to Mississippian marine carbonate rocks that make up about 25 percent of the Paleozoic strata exposed in the quadrangle (~2,130 m of the approximately 9,450 m) of Paleozoic strata exposed in the quadrangle). Thickness of stratigraphic units are from McDowell (1991), our own measurements, and from many of the stratigraphic reports and geologic maps listed in the references cited. Conodont biostratigraphic and color alteration index (CAI) analyses help identify stratigraphic units and structural discontinuities, particularly in the Upper Cambrian to Middle Ordovician chiefly carbonate rocks of the Shenandoah Valley and North Mountain fault zone. Conodont biofacies analyses provide additional information about the provincial affinities of the conodonts and the depositional environment of the rocks that contain them. Lithostratigraphic, biostratigraphic, paleoenvironmental, and CAI data for all conodont samples are given in table 1.