This study attempted (1) to determine the ability of children to translate four basic sentence patterns varied according to three levels of structural complexity (single words, clauses, and phrases filling sentence pattern slots), and (2) to determine whether this knowledge is related to their reading comprehension. A test of grammatical structure was designed using nonsense language sentences of four basic patterns: noun-verb; noun-linking verb-linking verb complement; noun-verb-object; noun-verb-indirect object-direct object or noun-verb-object-complement. The test of grammatical structure and the Paragraph Meaning subtest of the Stanford Reading Test were administered to 153 fourth-grade pupils. The results suggested that (1) the more basic elements a sentence pattern has, the more difficulty children have in identifying each element, relating it to other elements, and synthesizing the total into sentence meaning; (2) the more elements within a single sentence pattern slot, the more difficulty children have in relating these elements to the remainder of the sentence and synthesizing meaning; (3) knowledge of grammatical structure is an important factor in reading comprehension. (Author/LH)