Research has examined how Jews, Muslims, atheists, and agnostics react to feelings of social identity threat (i.e., the perception that one’s group is devalued or stigmatized). However, no research so far has compared reactions between religious minorities (RMs; Jews and Muslims) and nonreligious individuals (NRs; atheists and agnostics) in general. Concealment of identity appears to be lower among RMs than among NRs, although this possibility has not been directly tested. A pilot study was conducted to assess differences in identity concealment between RMs and NRs under social identity threat. Nonreligious individuals were more likely than Jews and Muslims to conceal their religious identity to avoid social identity threat. Furthermore, concealment was related to having less group identity (lower identity centrality). The main study replicated this effect with a larger sample. Implications for managing social identity threat among these groups and directions for future research are discussed.