Geder Olam is a treatise on modesty written by Rabbi Yisrael Meir HaKohen Kagan (known as the Chafetz Chaim after his work by that name), motivated by what he perceived as loosening standards of modesty, in dress and conduct, in contemporary religious society. Most of the work’s eight chapters focus on head-coverings for married women, but the importance, impact, and challenges of modesty in other realms are discussed as well, including a strong admonition against mixed-gender dancing.