System Justification Theory (SJT) proposes that members of disadvantaged groups perceive norms to express ingroup positivity. Adherence to these norms is assumed to result in open expressions of ingroup preferences on self-report measures while being unrelated to ingroup preferences assessed with indirect measures. We tested these assumptions with members of three disadvantaged groups: participants who identified as Gay or Lesbian (n = 196), as Black or African American (n = 202), or who reported higher weight (n = 208). We tested hypotheses on perceived norms and group attitudes at the individual level as well as at the social group level. While results at the group level suggest that differences in group attitudes between different disadvantaged groups are indeed related to differences in social norm perceptions between these groups, no consistent interrelations between norm perceptions and group attitudes were found at the individual level. We discuss the implications of these results, questioning SJTs basic postulate of group attitudes as manifestations of system justification processes in members of disadvantaged groups. We further argue that future research in this domain requires improved conceptual clarity in current theorizing, along with improved methodological operationalizations.