The belief in the gender invariance of many traits is a view that dominates much of psychology. In social psychology, this position is clearly represented by social dominance theory and the construct of social dominance orientation (SDO) where it is argued that, all else being equal, men will be higher in SDO than women. In other domains, though, these assumptions are being questioned, and researchers are arguing for a gender similarities hypothesis. The argument is that men and women are more similar than different, and where there are effects for gender, these are small. In this investigation, men and women are compared under similar cultural (Study 1), ideological, (Study 2) and status (Study 3) contexts to examine whether, all else being equal, men really are higher in SDO than women. In an additional study (Study 4), a meta-analysis is conducted aggregating the effect sizes of the previous studies. Results demonstrated either no effect for gender or an interaction between gender and the relevant social context and only a small effect size of gender—findings that disconfirm the ceteris paribus assumption of social dominance theory. In conclusion, the implications of the findings for understanding gender effects in social psychology are discussed. Copyright © 2011 John Wiley & Sons, Ltd.