An estimated 69 million more teachers are needed by 2030 to meet the scale of the educational challenges across the world, and especially in the Global South. Using current models of teacher professional development (TPD), it would take many decades simply to generate the quality of teaching professionals needed for universal basic education that can achieve good learning outcomes. Written by Diana Laurillard and Eileen Kennedy of the University College of London (UCL) Knowledge Lab, Policy Brief: The Digital Multiplier Model for Teacher Professional Development at Scale argues for the redesign of the current multi-tier cascade face-to-face model into a single-tier online “digital multiplier” model: i.e., using large-scale online courses or MOOCs to provide TPD directly to local teachers, supported in local face-to-face groups. The policy brief pushes for innovative pedagogic design by teachers in addition to digital infrastructure development. In general, it is argued that any intervention must take a holistic and systemic approach to addressing local conditions.