PurposeSocial inequalities in mental health can be captured by occupational situation and social class stratification. This study analyzes the adequacy of a classification of work and employment conditions and an adaptation of the Goldthorpe social class scheme in relation to mental health in Barcelona, Spain.Design/methodology/approachMultiple correspondence analysis (MCA) and hierarchical cluster analysis (CA) on working and employment conditions were used to empirically construct distinctive working groups. Through 2 logistic regression models, we contrasted the association between mental health and (1) the cluster of employment and working conditions (with 4 categories: insiders, instrumental, precarious and peripheral workers), and (2) a standard Spanish version of the Goldthorpe social class scheme. The performance of the 2 models was assessed with Akaike and Bayesian information criteria. The analyses were carried out using the Barcelona Health Survey (2016) including the labor force population from 22 to 64 years of age.FindingsWide inequalities were found in mental health with both class schemes. The empirical class scheme was more effective than the Goldthorpe social class scheme in explaining mental health inequalities. In particular, precarious and peripheral workers in the MCA-CA analysis, together with unemployed workers, emerged as distinctive social groups apparently masked within the lower social class in the standard scheme. When using the standard scheme, the authors recommend widening the scope at the bottom of the social class categories while shrinking it at the top as well as considering unemployed persons as a separate category to better represent mental health inequalities.Social implicationsThe working poor appear to report at least as much poor mental health as unemployed persons. Policies aimed at more inclusive work should consider job quality improvements to improve the mental well-being of the labor force.Originality/valueOur study examines the utility of social classes to explain mental health inequalities by comparing an empirically based social class to the Spanish adaptation of the Goldthorpe classification.