Groups, like individuals, can communicate. They can issue statements, make promises, give advice. Sometimes, in doing so, they lie and deceive. The goal of this paper is to offer a precise characterisation of what it means for a group to make an assertion and to lie. I begin by showing that Lackey’s influential account of group assertion is unable to distinguish assertions from other speech acts, explicit statements from implicatures, and lying from misleading. I propose an alternative view, according to (...) which a group asserts a proposition only if it explicitly presents that proposition as true, thereby committing to its truth. This proposal is then put to work to define group lying. While scholars typically assume that group lying requires (i) a deceptive intent and (ii) a belief in the falsity of the asserted proposition, I offer a definition that drops condition (i) and significantly broadens condition (ii). (shrink)