Based on the argument that the ingroup projection model may not be applicable to the minority group when addressing the effect of relative ingroup prototypicality (RIP) on outgroup attitudes, two studies investigated whether RIP and its effects on outgroup attitudes differ for the majority (Han) and an ethnic minority group (Tibetan). We measured RIP and outgroup attitudes in Study 1 (N = 164) and manipulated RIP in Study 2 (N = 145). The results indicated that the Hans presented high RIP, whereas the Tibetans presented low RIP. The effects of RIP on outgroup attitudes were moderated by group size: High RIP among Hans resulted in negative outgroup attitudes, whereas high RIP among Tibetans led to positive outgroup attitudes. These findings imply that improving the minority group’s RIP by making its culture prototypicality equal to that of the majority group would lead to positive outgroup attitudes.