Preindustrial social mobility is still primarily understudied in present times. Most preindustrial and early-industrial social mobility research focused strictly on occupational mobility, not fully capturing the substantial socioeconomic disparities within occupational groups that presumably always existed. In this study, we aim to contribute to the literature by estimating long-term trends in intergenerational social mobility in Barcelona and its hinterland. We use the Barcelona Historical Marriage Database to assess disparities between socially and non-socially mobile individuals within occupational groups through unique data covering occupational prestige and economic information via genealogical reconstitutions. Using a combined SES approach (occupational prestige and economic capacity) can capture both class differences and within-occupation disparities. Socioeconomic mobility increased since the beginning of the 18th century, during Catalan protoindustrialization, but with significant class disparities. SES persistence increased for Non-Manuals' children, stagnated for Artisans' children, and declined for Farmers'. Moreover, within occupational groups, we find that intergenerational class-mobile individuals had always been disadvantaged in socioeconomic terms compared to the immobile, a constant characteristic from preindustrial times until the end of the 19th century. These results suggest that socially immobile (intergenerationally) individuals always benefited from the privilege of having fathers within the same occupational class, independent of the period, which recalls the sociological concept of the class ceiling.