Increasing numbers of women are attracted to careers in the professional services. However, when their progress is considered to partner positions, it is found that they are not advancing to the levels anticipated. When the literature in relation to the partnership promotion process is explored, we find explanatory models are rare, and rarer yet is work that considers the impact of sex bias on the process. The article adds to the limited work available by presenting findings from a behavioural process perspective through an empirical study with male and female management consultants in a professional services firm which indicates that the promotion to partner process is indeed sex biased. Two areas of disadvantage for women are identified: the presence of a self-managed career advancement process necessitating a proactive approach to demonstrating individual contribution; and the need to ‘fit’ a prevailing model of success within the firm which is a masculine model and is more problematic for women. The article calls for a differentiated treatment of the glass ceiling phenomenon, capable of capturing disadvantage accruing from societally based factors and sector-based factors. The implications of the findings for future research and professional service firms are discussed.