This chapter examines the implications of liberalism for foreign policy and foreign policy analysis. Liberal countries have long been known to maintain peaceful relations with each other. Liberal democracies tend to respect and accommodate other democratic countries and negotiate rather than escalate their inter-liberal disputes. However, liberalism can also exacerbate tensions with non-liberal states. The chapter first considers what scholars have meant by liberalism before describing the major features of liberal foreign relations and the three schools of liberal foreign policy analysis: individualist, commercial, and republican. It then explores the effects of liberalism on the international relations of liberal states: incentives for a separate zone of peace among liberal states, imprudent aggression against nonliberals, and complaisance in vital matters of security and economic cooperation. It concludes with reflections on preserving and expanding the liberal peace — while avoiding war with the wider non-liberal world.