This study was designed to test the hypothesis that a behavioural programme was used preventatively to try to reduce crying and improve night sleeping in 1- to 12-week old infants compared with educational support or existing services. The objectives were to develop strategies which can be used to inform, help and support parents of new babies. The study was a three-group prospective randomized controlled trial in West Berkshire and South Oxfordshire, making a comparison between a behavioural policy, an educational intervention and existing services. The participants were 610 mothers giving birth to term healthy infants at the Royal Berkshire Hospital, Reading between March and November 1997. The main outcome measures were interruption-free nights i.e., the number of nights each week when parents reported that their baby slept for a minimum of 5 hours; babies' fuss/crying patterns; and mothers' general well-being and approach to parenthood. There were no significant differences between the groups in the amount of fuss/crying, which gradually reduced during the 12 weeks. At 12 weeks of age, more mothers in the behavioural group reported their babies to have had seven interruption-free nights (61%), compared with the educational (53%) and the control groups (50%). This was significant at the P < 0.05 level. The educational and control groups did not significantly differ at any age. At 6 and 12 weeks, mothers allocated to the behavioural policy were more structured in their approach to parenting and rated it more highly for convenience. At 9 months, their babies were more likely to have a regular bedtime routine. Where mothers followed a behavioural programme, 10% more babies slept for a minimum of 5 hours at night without disturbing their parents at 12 weeks of age. This improved sleeping pattern persisted up to 9 months of age. Mothers in this group also reported a greater feeling of control and increased confidence in their ability to cope. The more widespread adoption of a behavioural approach to the management of early infant sleeping should be considered.