Leo Strauss famously asserted that the fundamental, defining debate within Western civilization is that between Jerusalem and Athens, piety and philosophy, the Bible and Plato. And yet, surprisingly, Strauss never published any of his thoughts on Plato's dialogue on piety, the Euthyphro. This volume presents, for the first time, Strauss's 1948 notebook on the dialogue, written in preparation for a class at the New School for Social Research. Featuring close analysis and line-by-line commentary, the notebook opens a window onto a philosophic mind in action, as Strauss asks questions of the classic text and jots down observations and formulations but also steps back and reviews the overall movement of the dialogue. Beyond the notebook, the volume also brings together all the known materials that lay out Strauss's thoughts on the Euthyphro. This includes newly transcribed public lectures, illuminating appendixes, critical essays, an account of Strauss's public lecture, and a new English translation of Plato's Euthyphro. Engaging and inspiring, Leo Strauss on Plato's "Euthyphro" is a vital resource for anyone who studies Strauss.