Objective: Research has found corporal punishment to have limited effectiveness in altering child behavior and the potential to produce psychological and cognitive damage. Pediatric professionals have advocated reducing, if not eliminating its use. Despite this, it remains a common parenting practice in the US. Methods: Using a three-group randomized design, this study explored whether embedding educational information about typical child development and effective parenting in baby books could alter new mothers' attitudes about their use of corporal punishment. Low-income, ethnically diverse women (n = 167) were recruited during their third trimester of pregnancy and followed until their child was 18 months old. Results: Findings from home-based data collection throughout this period suggest that educational baby books compared with non-educational baby books or no books can reduce new mothers' support for the use of corporal punishment (respective effect sizes = 0.67 and 0.25) and that these effects are greater for African-American mothers (effect sizes = 0.75 and 0.57) and those with low levels of educational attainment (high school diploma, GED, or less) (effect sizes = 0.78 and 0.49). Conclusion: Given their low cost and ease of implementation, baby books offer a promising way to change new mothers' attitudes and potentially reduce the use of corporal punishment with infants and toddlers. (Contains 1 figure and 4 tables.)