This paper is the first generalizable empirical analysis of dual branding, i.e., supply of private label (PL) by national brand (NB) manufacturers. The authors compile a unique dataset combining the identity of PL suppliers in over 260 packaged good categories with multiple years of scanner data in the Spanish grocery market to offer several contributions. First, they provide new descriptive insights, e.g., on the prevalence of dual branding in categories where the manufacturer does and does not have NBs, the longevity of PL supply arrangements, and the differences in PL sourcing across retailers. Second, they integrate the literature on motivators and dissuaders of dual branding and test the impact of relevant manufacturer, retailer, and dyad characteristics on PL supply in NB and non-NB categories. The results reveal a more nuanced empirical reality than is evident from prior research regarding the role of multi-category scope, fighter brands, NB differentiation, and size and positioning of the retailer’s PL. Third, they examine the outcomes of PL supply for the NBs of dual branders and find that starting (terminating) PL supply to a retailer significantly benefits (hurts) the relative distribution depth but not the relative share of the dual brander’s NBs at that retailer.