The rapid shift online during the Covid-19 pandemic has put online learning firmly on the agenda of universities everywhere and to realise fully the transformative potential of online learning this book argues the need for an evidence-based design approach. The evidence comes from the experiences of online learners who are professionals: educators, engineers, medics and researchers. Designbased research, learner contributions, survey responses and interviews with these learners demonstrate that open, online, collaborative learning experiences are not only feasible but effective for building professional community knowledge. Innovative online learning of this kind can help universities contribute to the global public good by achieving high quality learning at scale. The open online platforms being used in the book widen global access to professional education and create more porous boundaries between universities and the wider community. This is critical for achieving, for example, the full impact of the current policy discussions on the UN SDGs, such as climate and inequality. The evidence-base shows how co-designed, transformative digital education can be mobilised to support professionals such as teachers in crisis contexts, government officials investigating renewable energy solutions, or medics adapting treatments to local conditions. It also shows how to scale up professional development in areas where expertise is urgently required. The book concludes that scaled-up online learning can enable HE to deliver on the UN SDGs by equipping citizens and communities with the knowledge and skills needed to solve the worlds most pressing problems.