This technical report serves as an appendix to a recent article by Byrne and Sholkovitz (1996) in the Handbook on the Physics and Chemistry of Rare Earths (vol. 23, chapter 158, pg. 497-592) edited by K. A. Gschneidner Jr. and L. Eyring and published by Elsevier Science. This article, Marine Chemistry and Geochemistry of the Lanthanides, discusses the physical chemistry of the lanthanides in natural waters, describes the major features of the lanthanides in rivers, estuaries and oceans and discusses the chemical and biogeochemical processes controlling the speciation and distribution of the lanthanides in the ocean. The article by Byre and Sholkovitz (1996) refers to a large set of published and unpublished data on the rare earth (RE) composition of rivers, estuaries, seawater, marine pore waters and marine hydrothermal waters. In order to conserve space in the Handbook arctile, a compilation of concentration data for natural waters will be presented in this report. Publications through 1995 are cited.