The double-deficit theory of reading disability (Wolf & Bowers, 1999) was examined in a sample of 56 reading-disabled and 45 normal-reading elementary school children (aged 8 to 11). As hypothesized, the two groups differed markedly on all phonological analysis tasks and on rapid continuous naming of digits and letters (the double deficits), but they differed as well on orthographic tasks, attention ratings, arithmetic achievement, and all WISC-III factors except perceptual organization. Within the reading-disabled (RD) sample, children in the double-deficit subgroup were no more impaired in reading and spelling than those with a single deficit in phonological analysis, and those with a single deficit in rapid naming were no more impaired than those with neither deficit. Multiple regression analyses suggest that a multiple causality theory of RD is more plausible than a double-deficit theory.