The Family Nurse Partnership (FNP) Programme is a structured intensive home visiting programme delivered by trained family nurses to nulliparous teenagers throughout pregnancy and until their child is two years old. Currently FNP is provided in over 60 primary healthcare sites in England with a planned capacity increase to 13,000 concurrent clients by 2015. Researchers from the South East Wales Trials Unit at Cardiff University are testing the effectiveness of FNP in England in the Building Blocks study--a randomised controlled trial funded by the Department of Health (DH). The trial team includes collaborators from the Universities of York, Bristol and Glamorgan.