The Discipline of Restraint examines the ethical, institutional, and civic dimensions of self-limitation in the exercise of power. It argues that restraint is not weakness, passivity, or indecision, but a demanding moral competence-one that requires judgment, patience, and the courage to resist certainty. Across its chapters, the book explores restraint as it operates within the inner life of decision-makers, inside institutions shaped by incentives that reward aggression over prudence, and in public life, where legitimacy depends on proportionality and self-command. Rather than celebrating action for its own sake, the book asks what is owed to consequence, responsibility, and those who live with decisions long after authority has passed. It challenges the assumption that power must always be exercised to be justified, and suggests instead that the long health of institutions and democracies depends upon the capacity to refrain. This volume forms the second part of the Command and Restraint trilogy, following Between Orders and Silence and preceding After Command. Together, the three works examine authority before, during, and after power-what it demands, what it distorts, and what remains when command ends.