  We measure the smoothness of the infrared sky using the COBE DIRBE maps, and
obtain interesting limits on the production of the diffuse cosmic infrared
background (CIB) light by matter clustered like galaxies. The predicted
fluctuations of the CIB with the DIRBE beam size of 0.7\deg\ are of the order
of 10\%, and the maps are smooth at the level of $\delta\nu I_\nu \sim $ a few
\nwm2sr rms from 2.2 to 100 \um. The lowest numbers are achieved at mid- to
far-IR where the foreground is bright but smooth; they are
$\sqrt{C(0)}$$\leq$$(1-1.5)$ \nwm2sr at $\lambda=$ 10-100 \um. If the CIB comes
from clustered matter evolving according to typical scenarios, then the
smoothness of the maps implies CIB levels less than $\sim (10-15) $ \nwm2sr
over this wavelength range.
