Universal screening in elementary schools often includes administering curriculum-based measurement in reading (CBM-R); but in first grade, nonsense word fluency (NWF) and, to a lesser extent, word identification fluency (WIF) are used because of concerns that CBM-R is too difficult for emerging readers. This study used Kane's argument-based approach to validation as a framework to evaluate the interpretations and use of scores resulting from screening 257 first- and second-grade students. First, scores from three word lists (decodable WIF, high-frequency WIF, and whole-word NWF) were examined as indicators of reading achievement. Then, the use of these word list scores was evaluated regarding their ability to classify at-risk readers accurately and as supplements to CBM-R during the winter universal screening period. Participants were also concurrently administered a norm-referenced measure of early reading skills and global reading achievement. Results suggested that the word lists were good indicators of reading achievement and provided support for using CBM-R or a word list in conjunction with CBM-R to discriminate among at-risk readers. Findings have implications for the administration of universal screeners in first and second grade.