2021 was a challenging year, both for the international development sector and for the world as a whole. The second year of the Covid-19 pandemic brought new development challenges and increased complexity. Significant cuts in the UK’s Overseas Development Assistance (ODA) means that interventions need to be more targeted, prioritised and strategic. In this uncertain landscape, having accessible, reliable and timely evidence and learning is more important than ever.The Knowledge, Evidence and Learning for Development (K4D) programme has continued producing rapid helpdesk reports and facilitating educational learning journeys for the Foreign Commonwealth and Development Office (FCDO) and its partners, sharing these outputs with the wider international development community.We have summarised key moments through the #K4Din2021 Year in Review campaign, reflecting on our impact and achievements.