Several pod characteristics were evaluated to select methods for determining optimum maturity for mechanical harvest of flat podded `Roma II' beans (Phaseolus vulgaris L.). The test was conducted over a 3-year period (1993-1995) at Crossville, Tenn. A total length of 3.6 to 4.4 inches (90 to 112 mm) for the center seed from each of 10 of the more mature pods was a rather reliable and rapid field guide for determining optimum maturity for mechanical harvest of `Roma II' bush beans.