We develop a spectral-theoretic harmonic analysis for an arbitrary UMD
space X. Our approach utilizes the spectral decomposability of X and
the multiplier theory for L(X)(p) to provide on the space X itself ana
logues of the classical themes embodied in the Littlewood-Paley Theore
m, the Strong Marcinkiewicz Multiplier Theorem, and the M. Riesz Prope
rty. In particular, it is shown by spectral integration that classical
Marcinkiewicz multipliers have associated transforms acting on X.