In the opening lines of Aristophanes' Acharnians, Dicaeopolis counts first among his greatest joys ‘the five talents Cleon coughed up’, and he professes his love of the Knights for this service ‘worthy of Hellas’. The ancient scholiast gave what he thought an obvious explanation from Theopompus (F 94): he tells us that Cleon was accused of taking bribes to lighten the tribute of the islanders, and he was then fined ‘because of the outrage (ὑβρ⋯ζειν) against the Knights’. Evidently Theopompus connected the charges against Cleon with some earlier proceedings instigated by Cleon against the Cavalry. There is, as often, some difficulty in determining what Theopompus said and what the scholiast inferred, and, aside from that editorial problem, the scholiast's all-too-simple solution faces at least three major objections regarding the legal and political implications of such a trial. On the strength of such objections it was long ago supposed that Dicaeopolis rejoices not at a recent political defeat for the demagogue, but in recalling a theatrical expose in Babylonians of the previous year. This theory of a stage trial, however, encounters obstacles of its own in any reconstruction of the lost play. In recent work there have been many comments but no altogether satisfactory solution on this problem. It is the view of many that Cleon indeed suffered some political defeat in the year preceding Ach.; but, by this approach, ingenious solutions are required to make sense of the scholia. The assumption of a stage-trial, involving the Knights and Cleon in Babylonians, is still found persuasive by others, but if we are to discount the fragment of Theopompus, which has supporting testimony elsewhere in the scholiastic tradition, we would like to have something more than mere inference that Cleon was tried and convicted in Babylonians. The purpose of this paper is to find a more cogent explanation for these lines in Ach. and the equally puzzling scenario in Theopompus. It will be helpful to begin with the broad outlines of the problem (section I), and then proceed to re-examine the prevailing views, the stage-trial theory (II) and historical theories based upon the scholia (III).