This small package allows a LaTeX document containing the citation commands provided by the package to be compiled using the package. Migration from harvard to natbib thus can be achieved simply by replacing

\usepackage{harvard}

with

\usepackage{natbib}
\usepackage{har2nat}

It is important that har2nat be loaded after natbib, since it modifies natbib commands.

The author is Bas Straathof.