  We propose a new form of dimensional reduction that constrains dilatation
instead of a component of momentum. It corresponds to replacing toroidal
compactification in a Cartesian coordinate with that in the logarithm of the
radius. Massive theories in de Sitter or anti de Sitter space are thus produced
from massless (scale invariant) theories in one higher space or time dimension.
As an example, we derive free massive actions for arbitrary representations of
the (anti) de Sitter group in arbitrary dimensions. (Previous general results
were restricted to symmetric tensors.) We also discuss generalizations to
interacting theories.
