The study researches how effective and sustainable the government’s programme of technology-supported, decentralised, and school-based Teacher Continuous Professional Development (TCPD) is in improving teaching and learning in rural primary schools in Tanzania. The study employs a design-based implementation research (DBIR) approach in its first phase, sharing the emerging messages with government to inform refinement of the national programme. We will then conduct a difference-in-differences study in the second phase, investigating any impact of change in teacher practices on student learning outcomes. We are also conducting a new study entitled “Assessing the scale-up of a technology-supported, government-led TCPD programme in Tanzania: Considering issues of equity, agency, and adaptation“, co-funded by IDRC and FCDO. The focus is on equitable participation of different teacher groups (especially considering gender, disability, rurality and connectivity/technology access), effectiveness of the implementation as the programme expands, and schools’ and individuals’ agency to localise the programme to suit their contexts.