The relationship between mothers' health beliefs and use of well-baby services among a poor, minority, high-risk population is reported. Data were collected from 61 black mothers attending a maternal-child clinic by interviews at the first and sixth months after the birth of their infants. The analysis focused on four health beliefs (susceptibility, severity, benefits, and efficacy) and two health behaviors (clinic visits and immunizations during the first 6 months). Although mothers' health beliefs were not predictive of clinic visits, health beliefs at the sixth month accounted for 30% of the variance in the number of immunizations. This relationship was dominated by perceived efficacy of immunizations and perceived benefits of well-baby services. The findings indicate a need to consider the nature and extent of possible changes in relationships between health beliefs and health behaviors over time.