Despite the relevance of systemic practice for repairing broken public systems, documented instances where it empowers marginalised groups en masse to be action researchers are rare. Public school systems that fail to educate millions of pupils are ripe for systemic inquiry. Using evidence, this article identifies conditions under which such inquiry fosters school system accountability and increases pupil learning. By tracing the emergence of a type of community scorecard practice called Citizen Voice and Action (CV&A), it explains how and why marginalised groups use CV&A’s systems-enhanced participatory research to engage with and reform unresponsive public systems. It also shows how soft systems thinking and further action research enhanced scorecard methodology. Brief case studies of CV&A use in Ugandan primary schools illustrate and explain how communities reform schools by using CV&A to systematically foster accountability. Discussion identifies how processes free them to create and use systemic knowledge. This theorising helps explain conditions under which systemic inquiry into school and other public systems is being generalised and scaled up.