The Adler Planetarium & Astronomy Museum in Chicago is home to one of the world's great collections of astrolabes. Roderick and Marjorie Webster, Adler Curators Emeriti, present the Western astrolabes from the Adler's collection. The earliest of these instruments dates from the 13th century, others are from the workshops of the greatest craftsmen of the Renaissance. All are described here and illustrated lavishly with photographs showing the front, the back and additional details such as the maker's signature. Introductory essays by the Websters and Sara Schechner Genuth explain the use of the astrolabe and its role in cultural and social history, while the appendices and bibliography provide information essential to the specialist.