Based on the local incidence and severity of motor vehicle occupant injuries, the authors' community and hospital injury prevention partnership identified child passenger safety for 4-to-8-year-old children as a priority. They designed a booster seat promotion campaign using an integrated social cognition model of health behavior. A series of focus groups were held with low-income African American, Somali, and Vietnamese parents to understand determinants of booster seat use in these communities. Deficits in understanding about the purpose of booster seats were seen in all groups, and concerns about cost and self-efficacy varied in important ways. Although legislation is an important tool in motivating child passenger restraint, most families saw safety as the prime reason to use booster seats with their children. These results illustrate the use of qualitative data to adapt a theory-based intervention to the needs of specific communities.