Chapter 4 argues that the concept of ‘measures of non-repetition,’ or ‘guarantees of non-recurrence,’ helps to navigate between critiques of transitional justice as it stands and the overexpansion of alternatives, such as transformative justice. The chapter sets out the origins and history of ‘guarantees of non-recurrence’ in the law of state responsibility. It continues by exploring now the concept has evolved, including how it is used in transitional justice (in existing truth seeking and reparations initiatives), and can be applied in ongoing cases (Colombia and southern Philippines). Roht-Arriaza concludes that non-repetition can address aspects of a transformative agenda (root causes and prevention, collective needs, the broadening of institutional reform to address social and cultural concerns, a focus on process and how reforms come about, etc.), building on existing principles and case law.