Traditionally female-dominated sectors are growing while traditionally male-dominated sectors are shrinking. And yet, sectorial male shares are not changing accordingly. Why don’t men enter female-dominated occupations? I study men’s selection into social work, a fast-growing occupation where the share of men has historically been below 25 percent. I embed a field experiment in the UK-wide recruitment of social workers to analyse barriers to men’s entry and the nature of men’s sorting into this occupation. I modify the content of recruitment messages to potential applicants to exogenously vary two key drivers of selection: perceived gender shares and expectations of returns to ability. I find that perceived gender shares do not affect men’s application decisions, which suggests no role for gender identity or social stigma in their choices. Increasing expected returns to ability encourages men to apply, and improves the average quality of the applicants and performance on the job of the new hires, indicating that men are negatively sorted into social work. In turn, a higher (perceived) share of male workers improves the quality of female hires by discouraging the least talented women from applying. These findings suggest that breaking barriers to men’s entry in female-dominated occupations may help employers increase the diversity and overall quality of their workforce.