Using data from the Labour Research Department's Payline bank of collective agreements, and drawing on case studies of the (male-dominated) rail transport and (female-dominated) food retail sectors, this article analyses agreement on enhanced work–family benefits, focusing on maternity and paternity leave and pay, and Shared Parental Leave (SPL) and pay. The opportunity structure for bargaining, consisting of internal and external factors encouraging or facilitating union engagement with work–family measures, has developed unevenly in the British case, resulting in only a small number of agreements overall. Collectively agreed provision offers significant benefits mainly for maternity leave and pay. The analysis finds evidence of a dynamic of bargaining whereby those organisations with enhanced maternity pay continued to extend provision and to introduce new enhancements for fathers through paternity leave, but also identifies the limits of this dynamic due to complexity of policy design. The article argues that trade unions can coordinate bargaining strategy even in the absence of formal mechanisms for doing so, but that local strategy depends on the external opportunity structure at all levels.