What is NATBIB? It is a LaTeX (2e, with some support for 2.09) package to act as generalized interface for standard and non-standard bibliographic style files (BibTeX). It is intended primarily to produce author-year style citations from a variety of non-standard .bst outputs; it therefore replaces the special and individual packages that go along with such .bst files: apalike.sty for apalike.bst et al. newapa.sty newapa.bst, chicago.sty chicago.bst, named.bst et al. harvard.sty agsm.bst, dcu.bst, kluwer.bst et al. astron.sty astron.bst, apa.bst, humanbio.bst, et al. authordate.sty authordate.bst, aaai-named.bst The standard .bst files (plain et al) and other numerical citation .bst files are also understood. There is also a native natbib format for .bst files, which is of course also understood. This is illustrated in the supplied natbib.bst file. For details, see the documentation by LaTeXing natbib.dtx. Patrick W. Daly Max-Planck-Institut f\"ur Aeronomie D-37189 Katlenburg-Lindau, Germany E-mail: daly@linax1.dnet.gwdg.de