Technical Abstract: The inheritance of blue pattern flower (BPF) expression was investigated in common bean (Phaseolus vulgaris L.). The BPF trait was derived from accession line G07262, and the flowers express blue banner petal and white wings with blue veins. Crosses between a BPF stock and three other parents - t pmic long micropyle stripe BC3 5-593, t z Fib arcus BC4 5-593, and t Z bipana Fib marginata BC3 5-593 - all segregated in F2 for either BPF or white flowers in a 9:7 ratio, respectively. Progeny tests in F3 from two of the crosses supported the hypothesis that two complementary dominant genes control BPF expression and permitted a genetic linkage estimate of cM = 32.4 ' 7.91 map units between pmic and one of the two genes for BPF. A cross between t z fib virgarcus BC3 5-593 and T Prpi-2 V BC2 5-593 demonstrated that t Prpi-2 did not express BPF. Two crosses - T Prpi-2 V BC2 5-593 x t pmic BC3 5-593 and 5-593 x a BPF stock - both segregated in F2 for plants expressing BPF in a 3/16 frequency. The combined experimental data demonstrated that a new gene tbp (bp = blue pattern) interacts with Prpi-2 to express BPF and that P is linked with Prpi-2 by 32 map units. The dominance order at the T locus is T > tbp > t. The pedigree source of the tbp gene and the heterogeneity of PI 632736 (t pmic long micropyle stripe BC3 5-593) are discussed.