I would like to know how to change the font size in the table of contents. Maybe make it 14pt or 16pt.

\documentclass[12pt]{report}
\begin{document}
\tableofcontents

\end{document}
-
Do you want it to be different from the other parts of the ToC? For example, what about the page and sectional numbers? – Werner Jul 21 '12 at 21:31
I want it to behave like the default, just bigger. I'm not sure but I think the section titles are a little smaller than chapter titles. If this is the case, I would like to preserve the difference. – ArcanaNoir Jul 21 '12 at 21:35

You can use the tocloft package and the command families \cftXfont (for the sectional number and titles) and \cftXpagefont (for the page numbers):

\documentclass[12pt]{report}
\usepackage{tocloft}

\renewcommand\cftchapfont{\LARGE\bfseries}
\renewcommand\cftsecfont{\LARGE}

\renewcommand\cftchappagefont{\LARGE\bfseries}
\renewcommand\cftsecpagefont{\LARGE}

\begin{document}

\tableofcontents

Some text in standard size just for comparison.

\end{document}

Instead of \LARGE you can use any other font size switch or \fontsize{...}{...}\selectfont.

Redefining also the family \cftXafterpnum will give you better spacing between entries:

\documentclass[12pt]{report}
\usepackage{tocloft}

\renewcommand\cftchapfont{\LARGE\bfseries}
\renewcommand\cftsecfont{\LARGE}

\renewcommand\cftchappagefont{\LARGE\bfseries}
\renewcommand\cftsecpagefont{\LARGE}

\begin{document}

\tableofcontents

Some text in standard size just for comparison.