Learning outcomes are low and instruction is poor in many low- and middle-income countries (LMICs). These shortcomings are particularly concerning given the substantial learning loss due to COVID-19 from which many systems are suffering. The Learning at Scale study identified eight of the most effective large-scale education programs in LMICs and now is examining what factors contribute to successful improvements in learning outcomes at scale (see list of programs on last page of this brief). These programs were selected based on their demonstrated gains in reading outcomes at-scale, from either midline or endline impact evaluations. The study addresses three overarching research questions, focused on understanding (1) the components of instructional practices (Brief 1), (2) instructional supports (Brief 2), and (3) system supports (Brief 3) that lead to effective instruction. This brief focuses specifically on system supports. It addresses the following research question: What system supports are required to deliver effective training and support to teachers and to promote effective classroom practices?