Following a historiographic overview, this article examines the meaning of the term imperium in the Politica (1589) of Justus Lipsius (1547–1606) by examining four separate contexts. First, this article examines vernacular translations of the Politica in the 1590s, published in English, French, and German. Second, the article examines the meaning of imperium within the context of Latin philology. Third, the article looks at the deployment of imperium in the Latin translations that Lipsius provides of Greek quotations within the Politica. Finally, the article examines imperium as the term is used in defining other terms within Lipsius’s political vocabulary in the Politica. The article concludes by situating its findings within the historiography of Lipsius’s political thought and suggesting that Lipsius deploys imperium across two semantic registers: as a term of order, command, or rule consistent with pre-Augustan Latin usage and as an architectonic or structuring term within Lipsius’s political vocabulary.