A psycholinguistic analysis of oral reading miscue substitutions and of silent reading cloze substitutions was used to compare five dimensions of the oral and silent reading processes: grammatical function, syntactic acceptability, semantic acceptability, meaning loss, and correction. Subjects were third and sixth grade students with high, average, and low reading ability. Four stories selected from a reading miscue inventory were each used in an oral reading test form and in a silent reading test form. Each subject was tested individually in two sessions on two separate days, receiving the oral test on one day and the silent reading test on another day. Among the study's findings were the following: (1) both reading processes seem to be similar, (2) reading processes appear to differ more among ability groups than between third and sixth grade readers or between oral and silent reading, (3) readers of varying abilities make a high number of substitutions that retain grammatical function, (4) readers of varying abilities seem to make high numbers of substitutions that are syntactically acceptable and low numbers that are unacceptable, (5) some differences between oral and silent reading are indicated by the semantic acceptability dimensions, (6) sixth grade readers make a smaller percentage of substitutions that are totally semantically acceptable at the story level than third grade readers during oral reading, and (7) readers of high ability make higher percentages of substitutions that are semantically acceptable at the story level than all other categories combined. (HOD)