In this thesis I argue that crowds can form morally evaluable collective intentions, even without formal decision making structures and that these intentions can direct morally evaluable collective actions. Although recent philosophical work in the area of collective moral responsibility goes some way to theorising collective agency and intentional action in crowds, we currently do not have theoretically sound basis for evaluating the blameworthiness or praiseworthiness of particular crowds, even though these evaluations are regularly made. This thesis attempts to fill (...) this explanatory gap in the literature. In developing this explanation, I make a taxonomic distinction between aggregative and cohesive crowds; a distinction that is based on a claim about the specific properties of a crowd that make it capable of bearing ascriptions of collective responsibility. Simply put, cohesive crowds are distinct from aggregative crowds because their members develop and share a specific bank of common knowledge. This knowledge can often be acquired very quickly and - crucially - may come to be shared without explicit verbal or written communication. It develops through a phenomenological experience of joint attention and a sharing of beliefs. While this common knowledge includes shared understandings of the crowd’s aims and goals, it also crucially includes knowledge of the relationships between crowd members and of the capacity that they have to act together. I argue that coordinated actions in crowds are only possible when individuals know that they stand in a certain relationship with each other. Their beliefs and intentions must be shared not merely in the sense that individuals possess the same beliefs and intentions but also that each person knows that they know that they share those beliefs and intentions with the people around them. I argue that crowds become cohesive crowds when their members together develop collective awareness of their beliefs and intentions. It is this specific epistemic condition makes possible the spontaneous coordination of individual actions towards a goal that only a crowd can achieve. (shrink)