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Pyramiding epistatic resistance genes to improve long term disease resistance has challenged plant breeders. Indirect selection using tightly linked markers will often facilitate the breeding of desired epistatic resistance gene combinations. In common bean, the most effective strategy for broad spectrum control of the bean common mosaic virus disease is to combine I, bc-u, bc-12, bc-22, and bc-3genes. We describe the use of near-isogenic lines and bulked segregant analysis to identify a marker tightly linked with the bc-12gene. The recessive bc-12gene conditions resistance to specific strains of bean common mosaic virus and bean common mosaic necrosis virus and is masked by the bc-22and bc-3genes. We identified a RAPD marker completely linked (0 recombinants) with bc-12, based on 72 F3progeny generated from a cross between the contrasting near isogenic lines (I + bc-1/I + bc-12). Segregation in this Igene background revealed that bc-12was dominant to bc-1in conferring resistance to top necrosis in the allelic series Bc-1> bc-12> bc-1. To facilitate marker-assisted selection of bc-12across breeding programs, the RAPD was converted to a SCAR marker, designated SBD51300. Tight linkage (0 recombinants) was confirmed in a second population of 58 F2progeny co-segregating for SBD51300and bc-12gene from a different source. Based on a survey of 130 genotypes, the SCAR will be useful for MAS of bc-12in most beans of Middle American origin and snap beans, but will have very limited utility in the case of kidney and cranberry beans. The SBD51300marker mapped on linkage group B3, revealing independence of bc-12from the Igene on B2 and bc-3gene on B6, which supports the opportunity to readily combine genes for broad spectrum and pyramided resistance to bean common mosaic potyviruses in a single bean cultivar.