This article asks how and when external factors influence domestic political change. Only a limited number of studies have dealt with this question systematically. This contrasts with rising popularity of the democracy promotion agenda among the policy-makers around the world. The article contends that external democracy promoters influence domestic processes of political change through two causal mechanisms: through constraining of autocratic agents and through empowering of democratic agents. The analysis reveals that external democracy promoters can be effective in influencing domestic change; but this depends on the causal mechanism at play and democratic propensity of the domestic regime.