The relation between Dynamic Indicators of Basic Early Literacy Skills (DIBELS) and reading comprehension at the end of first grade and second grade was examined in a sample of 1,518 first-grade students from a large urban school district. Receiver Operating Characteristic (ROC) analyses were used to determine optimal DIBELS cut scores for predicting satisfactory reading comprehension. A measure of reading rate and accuracy, a subtest that the DIBELS assessment refers to as Oral Reading Fluency (ORF), was a better predictor of comprehension than the remaining subtests, including a retell fluency task designed to measure comprehension. Also, use of other subtests in combination with ORF did not substantially improve predictive power beyond that provided by ORF alone. Vocabulary was an important factor in the relation between ORF scores and comprehension. Students with satisfactory ORF scores but poor comprehension had lower vocabulary scores than students with satisfactory ORF scores and satisfactory comprehension. (Contains 6 tables.)