This is the second in a series of three papers concerned with radiant heat transfer between people and their surroundings. While the first paper in the series was confined to human configuration factors, the second and third papers have much wider applicability. This particular paper is concerned primarily with the geometrical relationships determining radiant interchange within a rectangular enclosure containing an absorbing and radiating medium. Equations, tables, and examples are given for geometric mean beam lengths and configuration factors between parallel or perpendicular rectangles. Curves are also presented for the mean beam length between a small sphere and a rectangle which can be used to approximate the mean beam length between a person and a rectangular panel.