Much is being done by governments and organizations to help workers reconcile their family and employment responsibilities. One such measure has been the introduction of flexible working policies. While academic and policy debates focus on the barriers to flexible working, less consideration is paid to those who work alongside flexible workers. Through a gendered lens, this article focuses on professional women and explores the implications of UK flexible working policies for women's workplace relations in organizations that have traditionally been based on male models of working. Drawing on interviews conducted in three English organizations, it was found that the women's interests did not always coincide and that their social relationships, with respect to flexible working, involved both support and resentment. In particular, the women's interests were affected by organizational and job-related factors and their stage in the life course. These findings illuminate the ways in which policies are negotiated at the level of daily workplace life and show that co-workers are a pivotal part of the wider picture of flexible working.