Universal screening is the first mechanism by which students are identified as at risk of failure in the context of multitiered systems of supports. This study examined the validity and diagnostic accuracy of a reading computer-adaptive test as a screener to identify state achievement test performance for third through fifth graders (N = 1,696). Single time points and slopes within year and longitudinally were examined. Validity results for single points were moderate (0.60-0.79, p < 0.002). Validity for slopes and the state test were weak or not significant. Diagnostic accuracy cut scores that maximized sensitivity and specificity yielded high accuracy for single points whereas sensitivity was inadequate for slopes. Practical implications and future directions are presented.