The long-term impact on income inequality of agricultural commercial specialization is still an open-ended discussion. Diverse economic models and approaches offer competing views, while historians increasingly stress the contingent nature of the paths followed in the various contexts. Applying common inequality indices like the Theil index along with new ones such as the inequality possible frontier (IPF) and Inequality Extraction Ratios (IER), this study examines how winegrowing specialization in Catalonia correlated with agricultural income distribution in the municipalities of the province of Barcelona during the mid-nineteenth century. This analysis examines a large dataset assembled from over 86,000 cadastral taxpayers in 292 municipalities and recorded in the Distribution of Personal Wealth in Real Estate Ownership of the province of Barcelona in 1852, combined with other population and land use data listed in the Estadística territorial de la provincia de Barcelona (Land Use Statistics of the Province of Barcelona), compiled in 1858. The results confirm that inequality in agricultural income distribution was lower in predominantly winegrowing municipalities than in timber and cereal-growing ones, despite the fact that commercial specialization and higher population densities could have extended the inequality possible frontier of those winegrowing areas in the mid-nineteenth century.