This paper uses the concepts of ethnosphere and ethnodiversity to frame the stakes of cultural genocide in the context of the emerging global society. We are in an era of rapid global ethnodiversity loss. Global ethnodiversity is important because different cultures produce different solutions to the subjective and objective problems of human society, and because cultures have an intrinsic value. Rapid ethnodiversity loss is a byproduct of the expansion of the modern world-system, and Lemkin’s invention of the concept of genocide can be understood as a dialectical reaction to this tendency. The current phase of globalization creates pressures towards global monoculture, but movements towards polyculture can be observed. Genocide scholars have an interest in three underdeveloped lines of inquiry: measuring ethnodiversity loss; constructing valid measures of the vitality and life or death of cultures; and developing techniques for resolving social differences without the need for cultural consensus.