Genocide, global warming, organizational negligence, and oppressive social practices are four examples of moral contexts in which the interplay between individuals and collectives complicate how we are to understand moral responsibility. Moral Responsibility in Collective Contexts is a philosophical investigation of the complex moral landscape we find in collective situations such as these. Tracy Isaacs argues that an accurate understanding of moral responsibility in collective contexts requires attention to responsibility at the individual and collective levels. Part One establishes the normative significance of collective responsibility. Isaacs argues that collective responsibility is indispensible to providing a morally adequate account of collective actions such as genocide, and that without it even individual responsibility in genocide would not make sense. Isaacs explains the concepts of collective intention and collective intentional action, provides accounts of collective moral responsibility and collective guilt, and defends collective responsibility against objections, including the objection that collective responsibility holds some responsible for the actions of others. Part Two focuses on individual responsibility in collective contexts. Isaacs claims that individuals are not morally responsible for collective actions as such, but they can be responsible in collective actions for the parts they play. She argues that the concept of collective obligation can help to address large scale global challenges such as global warming, environmental degradation, and widespread poverty and malnutrition. Finally, Isaacs discusses cases of widespread ignorance and participation in wrongful social practice, whether it constitutes an excuse, and how to effect social change in those conditions.