  We examine the Sunyaev--Zeldovich (SZ) effect in the 7-yr Wilkinson Microwave
Anisotropy Probe (WMAP) data by cross-correlating it with the Planck
Early-release Sunyaev--Zeldovich catalog. Our analysis proceeds in two parts.
We first perform a stacking analysis in which the filtered WMAP data are
averaged at the locations of the 175 Planck clusters. We then perform a
regression analysis to compare the mean amplitude of the SZ signal, Y_{500}, in
the WMAP data to the corresponding amplitude in the Planck data. The aggregate
Planck clusters are detected in the 7-yr WMAP data with a signal-to-noise ratio
of 16.3. In the regression analysis we find that the SZ amplitude measurements
agree to better than 25%: $a=1.23 \pm 0.18$ for the fit Y^{wmap}_{500} =
aY^{planck}_{500}$.
