Women advocates and men critics: How referees' gender influences candidates' likelihood of receiving a promotion

External review letters (ERLs) play a critical role in the promotion and tenure (P&T) process. However, recently, scholars have questioned their validity, given the strong relationships between letter writer characteristics and letter content. Building on Madera et al. (2024), we develop a social role-based theory of how letter writer gender affects letter content and voting outcomes. Results from within-candidate analysis find gender differences in letters written for the same candidate, 1) men letter writers used more personal pronouns (I/me/myself) and women used more other-pronouns (she/he), 2) letters written by women - compared to men - had a more positive tone overall, and 3) used less doubt language. Collectively, this suggests that women write more supportive and candidate-focused letters than men in the P&T process. Confirming this, we find that - controlling for school, discipline, scholarly productivity, and demographics - candidates with a higher proportion of women letter writers (i.e., lower proportion of men) have more positive P&T outcomes. These findings underscore the need for P&T reforms to improve equity in the external review letter-writing and writer selection process. • Gender biases influence the content of external review letters (ERLs) in the promotion and tenure (P&T) process. • Women letter writers use less doubt language, fewer personal pronouns, more other pronouns, and a more positive tone than men. • A higher proportion of women letter writers is linked to fewer negative votes at the college level and a higher chance of provost approval.