When citing a group of 3 to 5 authors for the first time in a paper using the document class apa6, the command \citeauthor adds only the first author followed by "et al.". The APA manuscript guidelines (6th version) require to refer to all authors in the first citation of the document. \textcite and \parencite work as expected, though.
This is what I get:

This is how it should look like:

Here my example:
\documentclass[man]{apa6}
\usepackage[american]{babel}
\usepackage[utf8]{inputenc}
\usepackage[style=apa, backend=biber,doi,url]{biblatex}
\DeclareLanguageMapping{american}{american-apa}
\begin{filecontents}{literature.bib}
@article{foobar,
Author = {Foo, A. and Bar, B. and Baz, C.},
Journal = {Journal of Foo},
Pages = {1--2},
Title = {Foo is bar},
Volume = {1},
Year = {1999}
}
\end{filecontents}
\addbibresource{literature.bib}
\shorttitle{foo}
\begin{document}
\citeauthor{foobar}
% \textcite{foobar}
\end{document}
\citeauthor*{foobar}– Vivi Jun 15 '12 at 18:59apa6is not a package but a document class in LaTeX terminology. – Mico Jun 15 '12 at 19:43natbib=true(change the command in the preamble to\usepackage[style=apa, natbib=true, backend=biber,doi,url]{biblatex}and then using\citeauthor*{foobar}– Vivi Jun 16 '12 at 07:16\citeauthor*{foobar}always adds all authors. – deboerk Jun 18 '12 at 09:42