During Ocean Drilling Program (ODP) Leg 199, eight sites were sampled in the central tropical Pacific with a focus on Paleogene sediments along a transect on 56- to 57-Ma crust (Fig. F1). The sediments, deposited in the vicinity of the paleoequator, largely consist of a mixture of calcareous and siliceous sediments with lesser amounts of pelagic clay. Sediment density and velocity were routinely measured on core samples at all eight sites and were measured by borehole logging at Sites 1218 and 1219. The objectives of the analysis of the velocity and density measurements at Leg 199 drill sites are to evaluate the consistency of the various core and borehole measurements, to determine the extent to which velocity and density are controlled by sediment composition and burial history, and to estimate the in situ properties of the sediments. Establishing the relationships between density and velocity and estimating the in situ properties of the sediments also serves as a prelude for seismic modeling of the stratigraphy at the Leg 199 drill sites.