Recent scholarship often dismisses entrapment, arguing that there are hardly any identifiable cases; and that powerful states (protectors) can sidestep it by narrowing the treaty conditions under which they have to intervene to defend their weaker allies (protégés). Consequently, alliances and partnerships are nearly always considered risk-free assets. However, this paper argues that several types of entrapment are present. The paper is foremost concerned with classic entrapment, a type referring to a purposeful effort by the protégé to drag the protector into a conflict serving primarily the protégé’s interests. The protégé entraps the protector by placing itself deliberately in danger of defeat and by manipulating the protector’s domestic audience costs. Classic entrapment is likely to succeed under two conditions: (a) when the protégé’s allegiance confers the protector an advantage in a competition against other powerful states; and (b) in informal arrangements, in which there is no clear cut-off point to the protector’s commitment. The paper provides an illustration in the Ottoman Empire’s entrapment of Britain in the crisis preceding the Crimean War. The conclusion considers classic entrapment’s feasibility in present world politics, particularly in the context of Taiwan.