  Fluctuations in the cosmic microwave background (CMB) temperature are being
studied with ever increasing precision. Two competing types of theories might
describe the origins of these fluctuations: ``inflation'' and ``defects''. Here
we show how the differences between these two scenarios can give rise to
striking signatures in the microwave fluctuations on small scales, assuming a
standard recombination history. These should enable high resolution
measurements of CMB anisotropies to distinguish between these two broad classes
of theories, independent of the precise details of each.
