Young children's reading comprehension skill is associated with their ability to draw inferences (Oakhill 1982, 1984). An experiment was conducted to investigate the direction of this relation and to explore possible sources of inferential failure. Three groups of children participated: Same-age skilled and less skilled comprehenders, and a comprehension-age match group. The pattern of performance indicated that the ability to make inferences was not a by-product of good reading comprehension, rather that good inference skills are a plausible cause of good reading comprehension ability. Failure to make inferences could not be attributed to lack of relevant general knowledge. Instead, the pattern of errors indicated that differences in reading strategy were the most likely source of these group differences.