Why do states pay costs to engage in international competitions over issues of little immediate material or strategic interest to them? This dissertation argues that a substantial portion of state behavior, commonly attributed to security concerns, is actually driven by competitions for prestige. States often acquire territory or weapons or exert their independence in international affairs not out of concern for their security but out of a desire to persuade other states that they should be listened to. The dynamics of such prestige competitions are not well understood. Among my findings, I discover that states which have recently experienced a publicly humiliating event will be more likely to pay costs to seek prestige because they want to minimize decline in influence that might result from their demotion in the eyes of others. Also, if the humiliated state is near enough in influence to the dominant state in the system or region, the dominant state will match the humiliated state's prestige investment, generating an international race for prestige. These dynamics are illustrated within the Scramble for Africa and the nuclear arms race for parity during the Cold War.