Parenting programs can serve as effective interventions for improving child behavioral problems, strengthening parent-child relationships and promoting healthy development. However, family engagement remains a significant challenge and there is a need for practical and cost-effective solutions. This study was a randomized controlled trial to evaluate the effectiveness of an original, evidence-informed video which leverages communication science best practices to enhance engagement. Parents of children aged 2-8 years were recruited through Prolific (N = 250) and randomized to the engagement video or a standard-of-care informational video condition. After viewing the video, parents completed a battery of questionnaires about their expectancies for program helpfulness, program-related attitudes, parenting self-efficacy, anticipated commitment, and emotional and cognitive engagement in the video. Participants' engagement in the video (i.e., transportation) was tested as a potential mediator. Results showed that participants who viewed the engagement video reported greater expectancies for program effectiveness, higher parenting self-efficacy, stronger levels of anticipated commitment and more transportation into the video, compared to participants who viewed the informational video. Results further showed that transportation mediated all persuasive outcomes (i.e., expectancies, program-related attitudes, parenting self-efficacy and anticipated commitment), providing insights into why the engagement video was effective. Findings suggest that evidence-informed tools that absorb and engage people in the content can effectively shape parents' perceptions of parenting programs, help them feel capable to positively impact their child, and bolster their commitment to parenting change. Findings have implications for the development of future materials, and reveal the value of video-based tools that leverage visuals, storytelling, and modeling to engage families in treatment.