<p>Although socioeconomic status (SES) is related to students’ well-being, many studies consider only a single SES indicator and one dimension of well-being, providing an incomplete picture. The present study examined SES-related differences among a large sample of elementary school students in Germany. We employed multiple SES indicators, considered both cognitive and psychological dimensions of well-being, and explored potential underlying mechanisms. Our findings highlight that the relations between SES and well-being depend on the specific SES indicator and the well-being dimension under study: Family income was linked to both cognitive and psychological dimensions of well-being, but only when considered alone. In contrast, parental education remained relevant for cognitive dimension of well-being even when several SES indicators were considered. Parents’ occupation showed an association with one facet of cognitive dimension of well-being—school satisfaction—when analyzed alone. Regarding underlying mechanisms, several factors, such as parent-child communication, mediated the relations between SES indicators and both school satisfaction (a facet of cognitive dimension of well-being) and psychological dimension of well-being. However, no mediating effects were found for life satisfaction, the second facet of cognitive dimension of well-being under study. Future studies should consider that associations may vary depending on the chosen SES indicator and the well-being dimension of interest. In this context, further research on underlying mechanisms is needed to provide a more comprehensive understanding of social differences in childhood well-being.</p>