This document presents cross-sectional and longitudinal data relating the time required to read orally 50 unrelated letters, 50 unrelated words, and 100 words in text among first to sixth grade children and adults. Results include concurrent correlation between letter, word, and text times ranging between .18 and .92 with a median of .77. Longitudinal correlations between grades two and six ranged from .21 to .96 with a median of .78 indicating a high level of developmental stability and strong relationships between the abilities to read letters or words rapidly at an earlier age and reading text rapidly at a later age. Multiple regression analyses indicate that letter time variance is associated with a median of 46 percent of text time variance, while additional skills affecting word time variance is associated with a median of 27 percent of text time variance between grades two and six. These and the remaining results may be interpreted to indicate the existence of a developmental reading speed ability which is not primarily dependent on word identification or context-using skills. (Author/SW)