This book studies the properties of imperative clauses in the context of a theory of Universal Grammar. Daniela Isac argues that the specificity of imperative clauses cannot be the result of a unique imperative Force feature; instead, the `type' of imperative clauses can be traced back to a plurality of finer grained features, such as Modality and phi-features, hosted by the Mod, Infl, and Speech Event heads, among others. The data are drawn from a wide range of languages including various Romance, Slavic, and Germanic languages, as well as Finnish and Inuktitut. The analysis accounts for recurrent patterns in the interaction of imperative mood with phenomena like negation, restrictions on grammatical subjects, and the possibility of embedding imperative clauses. The approach, which focuses exclusively on morphosyntactic rather than semantic features, is potentially transferable to the analysis of other clause types, such as exclamatives, interrogatives, and declaratives.