We have studied the luminescence properties of microcavities which are formed by a single layer of poly(para‐phenylenevinylene) sandwiched between a dielectric mirror coated with a conducting indium tin oxide layer and a semitransparent metal electrode. Compared with a device without cavity structure, the spectral and spatial emission are significantly narrowed, and the forward emission intensity is enhanced. We measure a spectral linewidth (full width at half maximum) of the cavity modes of about 4 nm in photoluminescence and 20 nm in electroluminescence and an enhancement of luminescence intensity in the forward direction of more than an order of magnitude. The implications of the narrowing of the emission and possible transfer mechanisms for excitation energy are discussed. ©1996 American Institute of Physics.