The acquisition of school readiness skills upon kindergarten entry predicts children’s success later in life. Yet many parents, especially in under-resourced communities, lack confidence in their role as their child’s first educator. Public media-based interventions offer a scalable way to bring assistance into these communities, and likely effect change not only by teaching content but by influencing social norms and attitudes that support the target behaviors. This study utilized the reasoned action approach, based in social cognition, to evaluate a community intervention program designed to equip parents with skills they can use to support their children’s school readiness. Parents (n = 43) participated in the 4-week intervention program and completed assessments before and after participation. We hypothesized that program participation would positively affect parents’ attitudes and norms toward school readiness support behaviors, making those positive attitudes and norms more accessible from memory. Analyses utilized reaction time measures of attitude and norm accessibility. Findings suggest the program had measurable effects on the accessibility of injunctive norms about parenting. Additionally, open-ended data showed that parents felt they gained skills and confidence as a result of the program. Together, these findings suggest that bolstering social norms about positive parenting behaviors might be an effective area of focus for school readiness intervention programs, and they demonstrate that media psychology-based methods can be useful for demonstrating educational program effectiveness.