  (Abridged) Using the number and sizes of observed gravitational lenses, I
derive upper limits on the dark matter content of elliptical galaxies. Galaxies
built from Cold Dark Matter (CDM) mass distributions are too concentrated to
comfortably satisfy these limits; SCDM is ruled out, and LCDM is only
marginally consistent with the data. Thus, lensing adds to the evidence that
CDM mass distributions are too concentrated on kiloparsec scales to agree with
real galaxies, and extends the argument to elliptical galaxies. By contrast,
the lack of central images in radio lenses implies that the central densities
of CDM galaxies are too low on ~10 parsec scales, even if supermassive black
holes are included. Self-interacting dark matter, or any other modification to
regular cold dark matter, must simultaneously reduce the densities on
kiloparsec scales and increase the densities on parsec scales in order to
satisfy the unique constraints from lensing.
