# How to produce full author list in the first citation instead of “et al.” in *achicago* package?

I use the achicago package and need to produce full list of authors when a source is cited for the first time and then "et al." afterwords. I found that natbib has a longnamesfirst option that does that. Is this possible with achicago?

The answer is unfortunately: No. The achicago bibliography style does not provide means to have two different citation texts. It is also incompatible with natbib. The frankenstein bundle that contains achicago.bst is also quite outdated, no longer developed, and quite broken at places.

But there is an easy way out: use the chicago bibliography style instead. This is compatible with natbib:

\documentclass{article}

\usepackage{filecontents}
\begin{filecontents}{test.bib}
@book{a,
author = {A. First and B. Second and C. Third and D. Forth and E. Fifth and F. Sixth and G. Seventh},
title = {My book title},
year = 2013,
publisher = {Inhouse}
}
\end{filecontents}

\usepackage[longnamesfirst]{natbib}

\begin{document}
\cite{a}

\medskip

\cite{a}
\bibliographystyle{chicago}
\bibliography{test}
\end{document}