Purpose - The purpose of this paper is to contribute to assertiveness research and assess the differences in assertiveness as it relates to gender, national culture, and ethnicity. Design/methodology/approach - The data for the study are from 231 undergraduate students majoring in business at one of four academic institutions: three in the USA and one in the Republic of Vietnam. Students completed the 30-item Rathus Assertiveness Schedule. Findings - This research suggests that individuals who are alike in level of education and status demonstrate similar levels of assertiveness, regardless of gender, national culture, or ethnicity. However, differences were seen as the data show white American males to be the most assertive, with African American females next. White females ranked third, followed by Vietnamese females, concluding with Vietnamese males. Research limitations/implications - Although the sample size is small, the intent of this research was never to have the subjects represent the general population in terms of the variables used. Instead, the authors attempted to control for gender, culture, and ethnicity variables by using a sample of college students who were similar in relation to education and social status. Future research could more fully research the findings from this study which suggest that African American women are more assertive than all other groups with the exception of white males. Originality/value - This study also gives credence to the suggestion that the global manager, in order to become more effective, needs to fully understand employee differences as represented by gender, national culture, and ethnicity.