Just as there was a canon of three tragic dramatists, so the ancient world recognized a canon of three dramatists of Athenian Old Comedy: Aristophanes, of course, but also Cratinus and Eupolis. This article is chiefly concerned with Cratinus and Eupolis — a frustrating and unsatisfactory subject. Their plays are lost, and we have to rely on meagre fragments, preserved in quotations or on papyrus, and on various kinds of indirect evidence about their work. There is therefore very little that can be said about them, and even less that can be said with confidence. Nevertheless, the attempt to say something is worthwhile, in part because of the light that it may shed on Aristophanes' surviving works if we can discern something of the context in which he was working, but also because these men were evidently masters of their craft. One word of warning is in order: despite their mastery of the comic craft, uproarious entertainment is not to be expected from a paper on Cratinus and Eupolis; if jokes that have to be explained are notoriously unamusing, what can we expect of jokes that have to be reconstructed conjecturally before they are explained?