The article describes the background to, and implementation of, the Gauteng Primary Language and Mathematics Strategy (GPLMS) in South Africa from 2010 to 2014--an initiative aimed at system-wide instructional improvement in the Global South. Working in over 1000 underperforming primary schools in poor- and working-class communities, the government-led GPLMS combined scripted lesson plans, provision of quality learner materials and personalised instructional coaching to enable teachers to adopt more effective instructional practices.