Most summer squash, Cucurbita pepo L., produce one flower bud per leaf axil, whereas some genotypes can produce two or more. The former genotypes are referred to as single-flowering, whereas the latter are referred to as multiple-flowering. The objective was to determine the mode of inheritance of multiple flowering. The zucchini ‘True French’, which is single-flowering, was crossed with Accession 1777, a nearly isogenic line of this cultivar, which is multiple-flowering. Parental, filial, and back-cross plants were grown in pots in the greenhouse and each of their first 15 leaf axils was scored for the number of flower buds. Nearly all F1 plants, regardless of the direction of the cross, and plants resulting from back-crossing to ‘True French’ were single-flowering. Approximately one-fourth of the F2 plants, regardless of the direction of the cross, and half of the plants of the back-cross to 1777 produced two flowers at one or more leaf axils. These results indicate that the ability to produce more than one flower per axil is conferred by a single recessive gene, herewith designated multiple flowering, symbol mf.