NATO’s 1999 intervention in Kosovo was highly contested and seen as a turning point in international responses to mass violence. Making use of a new dataset on so-called “humanitarian military interventions” since the Second World War, the author examines the extent to which the Kosovo intervention has indeed initiated new trends. A comparison with other cases shows that NATO’s Operation Allied Force differed from other military interventions with a declared humanitarian purpose. Moreover, the author introduces a typology of humanitarian military interventions and proposes a new measurement of their outcome that can facilitate comparative research.