We have collected all the principal magnetostratigraphic data sets from both marine and terrestrial strata spanning the Paleocene/Eocene Series boundary. To assess the reliability of the data we use two simple measures (histogram analysis of polarity data; a jackknife parameter measuring dependence of a given polarity stratigraphy on sampling density). There are only sporadic magnetobiostratigraphic data, of questionable reliability, spanning the Paleocene/Eocene Series boundary in shallow marine/epicontinental sequences of northwestern Europe. There are several long marine sequences spanning the boundary, but there is poor consistency among the various ODP/DSDP sites, and the results are difficult to interpret. The most complete and reliable magnetostratigraphies from terrestrial sequences spanning the Paleocene/Eocene Series boundary appear to be those from the San Juan Basin, Ellesmere Island, and the Northern Bighorn Basin. The available magnetostratigraphic data clearly indicate that the Paleocene/Eocene Series boundary lies within Chron C24r. On the basis of poor documentation and suspected overprinting problems, we reject the term Oldhaven event (or subchron) used in reference to a short normal polarity interval within Chron C24r. However, there may be a different short normal polarity interval closely associated with the Paleocene/Eocene Epoch boundary, and possibly correlative with Cryptochron C24r.6 of Cande and Kent (1992); it may be represented by short normal polarity zones in at least one marine and two terrestrial sequences. If this short event is documented to represent a single magnetochron interval, it would subdivide the long reversed magnetozone (Chron C24r) within which the Paleocene/Eocene Series boundary has been shown to lie, and it would have great potential to improve local and global temporal correlations. Although much progress remains to be made, studies integrating radioisotopic dating, magnetostratigraphy, biostratigraphy, and stable isotope stratigraphy have greatly improved chronostratigraphic correlations and insights into the relative timing, and possible causes of biotic and physical events occurring near the Paleocene/Eocene Epoch boundary.