Dilys Cossey was secretary of the Abortion Law Reform Association from 1964-68, a member of the team which worked to reform the abortion law.  For the rest of her working life she remained active in the reproductive health, family planning and population field and played leading roles in campaigns for free NHS contraception, defence of the 1967 Abortion Act, promotion of embryo research, in establishment of the all-party Parliamentary  group on population, development  and reproductive health and the European Parliamentary Forum on population and development.  

She has held the chairs of FPA (1987-1993), Brook (1995-2001) and InteractWorldwide (2001-2004). In 1994 she was awarded the OBE and in 2000 the RCOG Faculty of Family Planning and Reproductive Health Care made her an Honorary Fellow.  From 1997-2003 she was a Board member of Ipas, an American NGO specialising in women's reproductive health.