Testimony is a source of knowledge. On many occasions, the explanation of one’s\ud knowing that p is that a speaker, S, told one that p. Our testimonial sources – the referents\ud of ‘S’ – can be other individuals, and they can be collectives; that is, in addition to\ud learning from individuals, we learn things from committees, commissions, councils,\ud clubs, teams, research groups, departments, administrations, churches, states and other\ud social groups. North Korea might make a declaration about its missile programme, the\ud church about the ordination of women priests, the council about its deficit, the research\ud group about its findings and so on. We will look at a few examples in detail shortly, but\ud the starting point is that social groups can be a source of testimony, and we can learn\ud things from such collective testimony. The question this paper pursues is: what explains\ud our learning that p from collective testimony to p?