Using data from three time periods (1981, 1987, and 1990/91), we analyze the factors that affect the hiring of female officers by municipal police departments. We find that affirmative action litigation significantly increased hiring of new female recruits, but female political representation in the form of female city councilors or mayors did not significantly affect the gender composition of police recruits. Consistent with co-worker discrimination, we find that hiring of female recruits is negatively related to the proportion of males already employed in the department. Furthermore, male-dominated departments are more likely to employ fitness exams for recruits (a potential barrier to women) than are more integrated departments. The effect of a police union is mixed; there is some evidence that unions boost the hiring of female officers, yet unions are also associated with an increased likelihood of using fitness exams to screen new recruits.