Summary A sample of 38 white working class primiparas intending to breast feed were alternately assigned to either an experimental or control group during the last trimester of pregnancy. All women were visited at home antenatally for a structured interview on their attitudes towards and information on breast feeding. The experimental group were visited twice more before the birth, seen within the first 5 days in hospital, and visited immediately after they returned home, to enable the provision of information, advice and support regarding breast feeding. All women were seen again at 3 months postpartum. There was a significant difference between the two groups in level of breast feeding success, and explanations for this effect are put forward in terms of the experimental intervention components.