Measurements of resonance absorption of neutrons were performed on single-absorber systems containing 238U and 232Th individually, and in binary systems containing mixtures of these two absorbers. The single-absorber measurements were made over a wide range of absorber concentrations and served as a check on the adequacy of resonance absorber calculations and/or resonance parameter data. The binary systems provided a situation in which the spacing of resonances is closer than in a single absorber, thus making questionable the usual assumption of separability of resonances. The measurements were performed by means of static reactivity techniques in the Advanced Reactivity Measurement Facility (ARMF-II) at the National Reactor Testing Station in Idaho. The calculated and measured values for the uranium dioxide systems are in good agreement over the wide range of absorber concentrations. The experimental results for the thorium dioxide samples are consistent with work by other experimenters but are in quantitative disagreement with resonance integrals calculated from a recent compilation of resonance parameters. The measured resonance integrals of the binary mixtures were smaller than the values predicted from the measurements on the single-absorber systems, indicating an interference effect of approximately 3% in the samples of highest absorber concentration. Calculations performed with a multiresonance version of Nordheim's ZUT code underestimated this interference effect between absorbers.