This article examines the biases the two most important senders of economic sanctions, the European Union and the United States, frequently introduce into their coercive measures. Distinguishing between sanction incidence and intensity, our study identifies the conditions under which the two senders over- or under-sanctioned their targets during the post-Cold War era. Theoretically, the authors conceive the executive branch of the two senders as opportunistic actors that balance the influence of special economic interests against the preference of the average citizen and the lobbying of public interest groups. Authors expect that senders shy away from harsh measures against allies and former colonies and that private interest groups try to prevent the imposition of strong sanctions that potentially harm their members’ business. However, strong diasporas from the target state and violations of core liberal values should increase the chance of forceful measures. Authors' examination of the post-Cold War era supports our demand- and supply-side analysis of the Western powers’ biased coercion. The measures of the two senders are often strikingly similar, reflecting the strong influence of the sanction bureaucracies of the two senders. However, a notable difference is that the EU imposes lighter measures against economically powerful targets. Counterfactual simulations demonstrate that the EU measures against Russia and the US sanctions against China have been repeatedly too weak during the post-Cold War era.