  We present first significant limits on WIMP dark matter by the phonon-light
technique, where combined phonon and light signals from a scintillating
cryogenic detector are used. Data from early 2004 with two 300 g CRESST-II
prototype detector modules are presented, with a net exposure of 20.5 kg days.
The modules consist of a CaWO4 scintillating ``target'' crystal and a smaller
cryogenic light detector. The combination of phonon and light signals leads to
a strong suppression of non-nuclear recoil backgrounds. Using this information
to define an acceptance region for nuclear recoils we have 16 events from the
two modules, corresponding to a rate for nuclear recoils between 12 and 40 keV
of (0.87 +- 0.22) events/(kg day). This is compatible with the rate expected
from neutron background, and most of these events lie in the region of the
phonon-light plane anticipated for neutron-induced recoils. A particularly
strong limit for WIMPs with coherent scattering results from selecting a region
of the phonon-light plane corresponding to tungsten recoils, where the best
module shows zero events.
