How do domestic political institutions affect the propensity to initiate international conflict? We improve theoretical understanding of and empirical knowledge on this question. We describe three major types of democratic institutional characteristics that have been hypothesized to increase the constraints on conflict initiation: public electoral participation, intra–legislative factors, and a stronger legislature in relation to the executive. Using a Generalized Estimating Equations (GEE) model to analyze 37 democracies in the period 1919–1992, we find that higher political participation levels decrease the likelihood of initiating an international dispute and that neither the number of parties nor the nature of the ruling coalition affects the likelihood of initiating a dispute. The evidence is mixed on whether variation in executive–legislative constraints makes initiation more likely. These findings highlight the significance of public consent for the formation of democratic foreign policy.