The conclusion provides three reasons for why the international development sector needs to act on side effects: (1) it stops preventable damage to human lives; (2) it helps disentangle dilemmas and pull the emergency brake when needed; (3) and it finally makes the discussion about aid effectiveness and efficiency an honest one. It then discusses the potential negative aspects of acting on side effects: the unintended effects of focusing on unintended effects. It debunks the arguments of those who claim that focus on side effects will lead to negative unintended effects with an elaborate ‘cheat sheet.’ Then, it provides concrete recommendations for the key target audiences of this book: policymakers, practitioners, and evaluators. It concludes with a final plea to protect international solidarity by transforming the international development sector.