As the world’s poorest people are increasingly concentrated in regions prone to extreme adversity, such as political violence, weak institutions and natural disasters, we need better knowledge of people’s behaviors and welfare outcomes under these conditions. We also need to understand better how policy and practical interventions can support human development best. ISDC collects and analyzes original micro-level information on human development indicators ranging from health, nutrition, food security and subjective well-being to education, employment and prosociality from around the world, with a focus on hard-to-reach and ‘hard-hit’ populations. We specifically analyze variation in these indicators due to exposure to extreme adversity and policy interventions, deriving evidence-based suggestions for better policies and practice.