  The first five years of operation of the multi-purpose experiments ZEUS and
H1 at the electron-proton storage ring facility HERA have opened a new era in
the study of vector-meson production in high-energy photon-proton interactions.
The high center-of-mass energy available at this unique accelerator complex
allows investigations in hitherto unexplored kinematic regions, providing
answers to long-standing questions concerning the energy-dependence of the rho,
omega, phi, and J/psi production cross sections. The excellent angular
acceptance of these detectors, combined with that of specialized tagging
detectors at small production angles, has permitted measurements of elastic and
inelastic production processes for both quasi-real photons and those of
virtuality exceeding the squared mass of the vector meson. This report provides
a quantitative picture of the present status of these studies, comparing them
to the extensive measurements in this field at lower energies and summarizing
topical developments in theoretical work motivated by the new data.
