Alberico Gentili was a significant academic lawyer of the late sixteenth and early seventeenth century. He was an Italian religious refugee who fled to England and became professor of law at Oxford. Among his works are three books on diplomacy dating from 1585. These have never attracted the same degree of interest as his other works and this article discusses both why this has been so and indicates ways in which they are worthy of more attention — particularly that they are peculiarly accurate representatives of the contemporary discussion of diplomacy and that there are two real and original contributions that Gentili made. One concerns the rights and privileges of resident ambassadors and the other rests on his clearly expressed conviction that diplomacy could know no bounds set by religion or culture. In both these opinions he was ahead of his time.