The debate over the population-conflict nexus has been dominated by scholars concerned with resource depletion as a result of population pressure, arguing that armed conflict can erupt over scarce resources. Empirical studies assessing the role of environmental and population factors in inter-state and domestic conflict only give limited support to the hypotheses that large population growth and high population density make countries more conflict prone. This study attempts to go beyond crude population measures and the debate about environmental scarcity. It has been argued that population pressure in the form of large youth cohorts, ‘youth bulges’, increases a country’s likelihood to experience outbreak of domestic armed conflict when these youth groups are excluded from political and economic participation. This claim is investigated empirically in a large-N event history analysis, using newly available UN demographic data and data for domestic armed conflict with a low threshold for violence. The rather robust results of the analysis support the hypothesis that large youth bulges, especially when they reach a certain threshold value, can contribute to outbreak of domestic armed conflict. Furthermore, the effect of large youth bulges on conflict propensity varies with the level of democracy in a state.