Dr. Cissy Ballen will describe large-scale experimental and observational efforts across institution types and geographic regions that show how certain features of the introductory science classroom create barriers for historically underserved students. This explanation forobserved performance disparities, the “course deficitmodel”, considers the negative impact of environmental conditions on student learning and participation. Dr. Ballen will demonstrate how some of these barriers can be mitigated by instructional and institutional choices that promote the academic excellence for all students across science disciplines.