G. L. Sewell Off-diagonal Long Range Order and Superconductive Electrodynamics (67K, TeX) ABSTRACT. We present a general, model independent, quantum statistical derivation of superconductive electrodynamics from the assumptions of off-diagonal long range order (ODLRO), local gauge covariance and thermodynamic stability. On this basis, we obtain the Meissner and Josephson effects, the quantisation of trapped magnetic flux, and the metastability of supercurrents. A key to these results is that the macroscopic wave function, specified by the ODLRO condition, enjoys the rigidity property that London envisaged for the microstate of a superconductor.