In recent years, multilateralism has faced significant challenges. The rise of populist sentiment in western countries, trade wars and now slowing economic growth have undermined trust in multilateral institutions including those of a plurilateral summit form. The Group of Twenty (G20) often faces criticism for its ineffective problem-solving and members’ poor compliance with their summit commitments. Yet evidence from the G20 Research Group shows that G20 members do comply solidly with the commitments they make at one summit before the next one takes place. Some summits and subjects have secured higher compliance than others. Understanding what causes compliance and how it can be improved is essential for improving G20 effectiveness, credibility and even its future. This study offers an exploratory quantitative analysis of performance at G20 summits. It relies on established conceptual frameworks and presents a descriptive inferential argument. Compliance coincides with, and thus might be improved by, making more summit commitments, holding ministerial meetings and using specific catalysts in the commitments, given the prevailing reciprocity in compliance among members rather than a single dominant actor such as the U.S. or China setting the pace.