  We give an explicit description of the spectrum of the Hodge--Laplace
operator on $p$-forms of an arbitrary lens space for any $p$. We write the two
generating functions encoding the $p$-spectrum as rational functions. As a
consequence, we prove a geometric characterization of lens spaces that are
$p$-isospectral for every $p$ in an interval of the form $[0,p_0]$.
