Preventive perinatal home visits are a powerful and effective tool, particularly for reaching the most vulnerable families. These families, who have multiple psycho-social difficulties, seldom use the available medical and social institutions and find themselves at greater risk of developing disorders in early parent-child relationships, as well as a subsequent psychopathology. This paper is based on a literature review of home-visiting programs, in France and other countries. Our purpose is both to better describe this practice, which has not yet been clearly formalized within institutions, and also to assess its impact and limitations.