This paper reports on an approach to practice development in breastfeeding as part of a national programme of work to address inequalities in maternal and child nutrition. The production and dissemination of evidence and guidelines is necessary but not sufficient on its own to effect change in practice, particularly when dealing with complex public health issues. In the case of breastfeeding, review evidence and national guidance have shown that multifaceted changes are essential if policy aspirations are to be realized. The objectives of the programme described here were to (1) inform and enable practice development in breastfeeding in low-income areas; (2) evaluate the impact of approaches used; and (3) develop robust approaches and appropriate material for use nationally. A conceptual framework was established, and a six-stage process is outlined. The recruitment of four sentinel sites across whole health economies, involving professionals and the voluntary sector, was an essential component of the programme. The strength of the model is that it provides a structured, cross-sectoral approach to practice development in public health. A key challenge is to identify whose responsibility it is to resource practice development when a number of disciplines and sectors are involved. This question needs to be addressed if public health guidance is to be of sustained benefit.