Objectives: To increase booster seat use among low income parents. Design/methods: A pre-test/post-test design conducted in nine daycare centers with post-test observations four to eight weeks after the intervention. Intervention: Parents who participated in an educational training received free seats, educational programs were provided to all daycare staff and children, and signs in parking lots informed parents about child restraints. At seven centers, new policies recommended compliance with state restraint laws. Parents at four centers randomly chosen from the seven received financial incentives if observed using booster seats. Main outcome measure: The percent of children aged 4-8 riding in booster seats. Results: Pre-test observations of 185 4-8 year olds found 56% riding unrestrained and fewer than 3% riding in booster seats. After the intervention, observation of 146 children found the number riding in booster seats increased to 38% and the number observed without restraints decreased to 26%. Most booster seat use occurred with 4 and 5 year olds. No 7 or 8 year olds rode in booster seats. Changing center policies to recommend compliance with state restraint laws and an offer of financial incentives appeared to have no additional impact. Conclusions: Booster seat usage among low income families can be increased dramatically, though use decreases with age. Providing free seats accompanied by training may be sufficient without the need for additional intervention.B ooster seats, vehicle child restraints that position small children who have outgrown child safety seats so that standard seatbelts can protect them more effectively, are the recommended restraint system for children over 40 pounds (18.2 kg) in weight and less than 57 inches in height (144.8 cm).1-4 These parameters encompass many children between the ages of 4 and 8 years of age who do not always fit properly in adult lap/shoulder belts unless they are elevated with the assistance of a booster seat. Nonetheless, studies have found that only about 5% of parents with children aged 4-8 use booster seats.5 6 A more recent survey found increased use over the last two years, though the authors caution that their data are based on telephone reports from drivers of vehicles in which children were injured and may be biased by ''over-reporting of restraint use ''. 7 Motor vehicle crashes kill more children in the 4-8 age group-roughly 500 children between 1994 and 1998-than any other source of unintentional injury. 8 In 2000, nearly half of the 4-8 year olds killed in crashes were unrestrained. 9Wearing adult seatbelts in the back seat or using a belt positioning booster seat greatly reduces the risk of fatality to 4-8 year olds. 9 However, a recent survey of parents of 4243 children involved in crashes found that for 4-7 year olds, the odds of injury were 59% lower when riding in belt positioning booster seats than when using seatbelts alone. 10Instances of premature use of adult seatbelts, failure to use booster seats, and the absence of any restra...