Declamation in ancient Rome was a rhetorical exercise through which young men gained facility at public speaking. It was a fundamentally creative activity, but at the same time subject to constraints that channeled this creativity in particular directions. This dissertation focuses on a type of declamation known as the controversia, in which the student was presented with a fictional legal controversy and had to make a court speech on behalf of either the prosecution or the defense. It studies how the themata (“themes,” or fictional scenarios) of these exercises invited different types of responses – argumentative, narrative, emotional, character-driven, utilitarian, and so forth – from the speaker. The combination of creativity and constraints provided training in moral reasoning and social valuation in addition to practical skills for courtroom advocacy. Many puzzling features of the genre make sense when compared with other Roman discursive practices, such as the use of historical exempla (“examples”) in ethical decision making, the assertion of control in literary translations of Greek texts, and the use of legal fictions in jurisprudence.