Educators, parents, and policymakers agree on the need to assess children’s learning to inform literacy teaching practices but are often divided about how best to gauge literacy development. In ensuing debates, school data walls have become pedagogically and spatially contested sites. We think of data walls as -scapes and scopic regimes that have sociomaterial force and that coalesce as complex assemblages worth interrogating. On that basis, our aim is to consider two kinds of data wall by drawing from a three year study of literacy teaching practices in government schools in one Australian state and sharing insights with resonance in similar education systems. Analysis shows that the first, more common data wall mapped and privileged quantitative data about, and summative testing results for, children and functioned primarily as an accountability tool. The second data wall added layers of qualitative data and formative assessment and facilitated valuable professional learning and development in support of children’s learning outcomes. Our findings are significant because they reveal how data walls foster integrative approaches to literacy assessment that cut through the debate. Findings also furnish theoretical insights about how data walls are powerful assemblages, enable sound educational outcomes, but require ongoing attention to their sociomaterial effects.