Technical Abstract: White mold, caused by the fungus Sclerotinia sclerotiorum (Lib.) de Bary, is a serious disease in common bean (Phaseolus vulgaris L.) causing significant yield loss. Few cultivars with high levels of physiological resistance to white mold have been described in common bean. The objectives of this study were to: (i) determine variation in aggressiveness for the local S. sclerotiorum isolates, and (ii) identify sources of resistance against local isolates using the greenhouse straw test. The evaluated materials included 199 accessions of a core collection established from the main bean genebank in Spain and 29 known cultivars or lines, five of them described as resistant sources to white mold: G122, PC50, A195, Cornell 606 and, MO162. Significant differences for aggressiveness among the four S. sclerotiorum isolates were detected. Generally, isolates 1 and 3 were more aggressive than isolate 4. Eighteen new sources of putative resistance to white mold were found; 11 accessions from the core collection and 7 cultivars or lines from known materials. To confirm resistance, the 18 select genotypes were tested using a more severe straw test with reactions evaluated 21 days after inoculation. All 18 genotypes exhibited less disease than the resistant check G122. The logical next step will be to evaluate the 18 genotypes for field reaction to white mold and conduct inheritance studies.