  In this paper, we prove that all doubling measures on the unit disk
$\mathbb{D}$ are Carleson measures for the standard Dirichlet space
$\mathcal{D}$. The proof has three ingredients. The first one is a
characterization of Carleson measures which holds true for general reproducing
kernel Hilbert spaces. The second one is another new equivalent condition for
Carleson measures, which holds true only for the standard Dirichlet space. The
third one is an application of the dyadic method to our settings.
