Does data use make a difference in student achievement? Despite the field's optimism on this matter, relatively few studies have attempted to quantify the effects of data use. These studies have often used the presence of a data use intervention (e.g., a data system or data coaching) as a proxy for use, as opposed to tracking teachers' direct interactions with data, via data system click logs, for example. Accordingly, the present study sought to address this methodological gap by exploring the 2-year effects of data use through a multilevel cross-classified model of teachers' system interactions and student achievement. A significant relationship was found between system use and elementary reading, but no significant relationships were found for elementary math, junior high math, or junior high reading. The implications of this study on how to conceptualize and measure use, as well as how to support practitioners, are discussed.