Augustine famously defends the justice of killing in certain public contexts such as just wars. He also claims that private citizens who intentionally kill are guilty of murder, regardless of their reasons. Just as famously, Augustine seems to prohibit lying categorically. Analyzing these features of his thought and their connections, I argue that Augustine is best understood as endorsing the justice of lying in certain public contexts, even though he does not explicitly do so. Specifically, I show that parallels between (...) his treatments of killing and lying along with his “agent (auctor)–instrument (minister)” distinction, in which God is the true agent or “author” of certain acts and humans are merely God's instruments, together imply that he would regard certain instances of public lying as permissible and even obligatory. I buttress my argument by examining several key but neglected passages and by responding to various objections and rival interpretations. Throughout, I challenge standard interpretations of Augustine's ethics of killing and lying and seek to deepen our overall understanding of these dimensions of his thought. In so doing, I contribute to ongoing discussions of public and private lying and to the task of relating Augustine's thought to contemporary debate and deliberation on war, killing, and lying. (shrink)