This study of 397 children provides qualified support for the work of Martin and colleagues in that kindergarten measures of negative emotionality and activity level were correlated with Grade 1 reading measures. The amount of reading achievement variance accounted for by temperament was less than that reported by Martin, however. Our analyses, nevertheless, revealed that persistence plays a significant role in accounting for reading progress. However, intelligence was found to be a moderator variable between persistence and reading achievement. For children with lower intelligence only, persistence significantly predicted reading achievement, the correlation being positive. Using growth curve analysis, we also found that persistence measured in kindergarten was a significant predictor of the growth rate of reading ability for children from kindergarten through third grade. The implications of these results for school psychological assessment processes, classroom instruction, and primary prevention are discussed.