This chapter is concerned with what was introduced in Section 2.2 as 'take-it-or-leave-it’ committees. The take-it-or-leave-it scenario is explained in detail in Section 3.1. In Section 3.2 we introduce the basic notions of ex post (i.e. after a vote) success and decisiveness. Section 3.3 introduces the probabilistic representation of voters' behaviour or preferences, which provides a formal setting for addressing the likelihood of decisions being passed, the likelihood of success and that of decisiveness in Section 3.4. The normative goal leads to the assumption that all vote configurations are equally probable, which provides a common perspective in which several ‘power indices’ in the literature are seen as assessments of the likelihood of being decisive or of being successful in a take-it-or-leave-it committee (Section 3.5). The conceptual and analytical distinction between the notions of success and decisiveness is discussed in Section 3.6, where arguments in support of the notion of success as the relevant concept in the take-it-or-leave-it scenario are given. The question of the optimal voting rule in a take-itor-leave-it committee is addressed in Section 3.7. Two points of view are considered: egalitarianism and utilitarianism, and the recommendations that stem from each of them are presented. The question of the optimal voting rule from either point of view is also addressed in Section 3.8 for committees of representatives.