We report on a study of the invariant mass spectrum of the hadronic system in the decay {tau}{sup -}{yields}{pi}{sup -}{pi}{sup 0}{nu}{sub {tau}}. This study was performed with data obtained with the CLEO II detector operating at the CESR e{sup +}e{sup -} collider. We present fits to phenomenological models in which resonance parameters associated with the {rho}(770) and {rho}(1450) mesons are determined. The {pi}{sup -}{pi}{sup 0} spectral function inferred from the invariant mass spectrum is compared with data on e{sup +}e{sup -}{yields}{pi}{sup +}{pi}{sup -} as a test of the conserved vector current theorem. We also discuss the implications of our data with regard to estimates of the hadronic contribution to the muon anomalous magnetic moment. (c) 2000 The American Physical Society.