The NHS has emphasised the need for rigorous evaluations of preventative home-visiting support (Bull and others, 2004) in building a public health evidence base. Interdisciplinary studies involving the NHS in any capacity are subject to ethical review by NHS Research Ethics Committees. However, the current process of ethical review does not respond flexibly to research conducted by non-NHS organisations. Through documentary analysis, this paper describes the experience of a non-clinical research evaluation of a family support service offered during pregnancy and the difficulties encountered in gaining ethical approval. Implications for social science research with minimal NHS involvement are discussed and recommendations for improvements suggested.