Cn. Domitius Annius Ulpianus (170-223 CE) was a prominent Roman jurist, magistrate, and occasionally a member of the imperial inner circle. He is the most cited jurist in Justinian’s Digest. Ulpian composed his treatise on the duties of the proconsul, along with much of his juristic corpus, between 213 and 217 CE, in the aftermath of the enactment of the Constitutio Antoniniana , in the formulation of which he may have been involved. The work addresses all responsibilities of the provincial governor as both an embodiment and representative of the Roman judiciary within his assigned province. It is the most detailed treatise on provincial governance to have survived. Moreover, Books 7-9 provide a rare exposition of Roman criminal law. Like the works of most jurists cited in Justinian’s Digest (with the exception of Gaius’ Institutes), Ulpian’s treatise survived primarily through the mediation of the Digest 's compilers. However, this treatise was also used by the compilers of at least two other late antique legal works: the Collatio Legum Mosaicarum et Romanarum and the collection known as the Fragments Vaticana . Additionally, the Christian author Lactantius referenced this work. Following in the footsteps of Otto Lenel, this edition utilizes all available sources and offers an extensive commentary on all aspects of the work and text, as well as a translation and detailed Introduction.