Research on academic pay finds an unexplained gender pay gap that has not fully dissolved over time and that appears to increase with years of experience. In this study I consider how role congruity bias contributes to this pay gap. Bias is more likely to manifest in a context where there is some ambiguity about performance and where gender stereotypes are stronger. I predict that bias in the attribution of credit for coauthored research leads to lower returns to research for female professors. To test this prediction, I use a sample of Canadian faculty in accounting, where research is typically coauthored, where females are underrepresented at the most senior ranks, and where many universities evaluate merit in research, teaching and service to determine salary increases. In regressions of salary on individual and institutional determinants of salary, I find that women earn marginally less than men. However, the gender gap is only evident for women who publish in a selective list of journals; for the subset of faculty with no publications from this list, there are no significant differences in salary. For researching faculty, the pay gap relates specifically to research productivity. While women publish less on average than men, the returns to their research are also lower. In particular, the relation between the individual’s research ranking and salary is significantly lower for women who publish a higher proportion of their work with men, than for all other faculty. Additional analysis of salary and coauthor patterns confirms that women receive significantly less credit for coauthored articles they publish with men than those they publish with other women but that no similar variations in reward are evident for men across publishing patterns. These findings suggest bias in the attribution of credit for coauthored research in the determination of salary, consistent with role congruity theory, and provide an important potential explanation for why salaries for women vary systematically from those of men even after considering productivity. Providing lower rewards for equal work represents a continuing ethical issue in academe and compounds the challenges already facing women in the profession.