This report captures what might be learnt from a selection of the world's most interesting examples of technology-assisted in-service professional development in lower-income countries and from wider reflections about the potential of technology to enhance the professional learning of teachers. This report explores the literature surrounding technology for professional learning, identifying six promising case studies: (1) UNESCO projects in Pakistan and Nigeria -- using mobile phones to deliver pedagogical content to early-grade and primary school teachers; (2) English in Action, Bangladesh using mobile phones and SD cards to deliver content to teachers; (3) Teacher Education in Sub-Saharan Africa (TESSA) -- OER [Open Educational Resources] to support interactive teaching practice; (4) Teacher Education through School-based Support in India (TESS-India) -- OER to support the adoption of more engaging pedagogies; (5) Teachers for Teachers, Kenya -- using mobile technology to strengthen teacher development in Kakuma Refugee Camp; and (6) National Tablets Programme, Kenya -- improving the coaching provided to teachers. Through these case studies we have made a series of reflections on the impact technology can have on teacher professional development, particularly in low- and low-middle income contexts: (1) Promising technology is not enough, we must not forget the human factor; (2) Mobile technologies have high potential to improve the reach, scalability and flexibility of teacher professional development; (3) OER constitute a promising format for professional development resources; (4) High-impact, sustainable technology-enabled solutions depend on local partnership and a sense of local ownership; and (5) The design and delivery of effective technology-enabled professional learning depends on high-quality impact data and careful piloting solutions. Our report explores each of these case studies and reflections in greater detail, drawing lessons for policymakers, practitioners and other organisations who seek to provide technology-related professional development opportunities for teachers.