Key Social Norms Take-aways This study shows that digital platforms like Facebook Messenger can be leveraged to shift social norms around gender and violence against women. Format matters: a fictional, humorous video series reduced regressive gender attitudes and acceptance of violence against women, while a documentary format was more effective in motivating public action. Subtle, story-driven content appears better suited to prompting internal attitudinal change, whereas direct messaging supports social engagement and behavior. Objectives: The study aimed to evaluate whether exposure to two different video-based social marketing interventions—one implicit (fictional) and one explicit (documentary)—could reduce the acceptability of violence against women and regressive gender norms, and promote prosocial behaviors related to anti-violence advocacy among young adults in India. Methods: A randomized controlled trial was conducted with 5,588 Facebook users in India, aged 18–35. Participants were randomly assigned to receive either a fictional video series, a documentary series, or placebo content over 10 days via Facebook Messenger. Pre- and post-intervention surveys measured attitudinal shifts, and medium-term behavioral outcomes were tracked using Facebook activity data, including profile frame adoption and video sharing. Intervention Details: The implicit intervention was a five-part fictional drama using humor and relatable scenarios to embed messages around gender equality and non-violence. The explicit intervention included four documentary-style videos featuring direct messages, expert voices, and calls to action. Both were designed for mobile viewing and delivered as chat-based sequences to simulate private, conversational engagement. Results: Participants exposed to the fictional series showed a 0.20 SD reduction in support for regressive gender norms and a 0.17 SD drop in acceptability of violence against women. Documentary viewers were 91% more likely to adopt an anti- violence against women profile frame and more likely to seek or share related content. There were no significant differences in impact across gender, education, or urban-rural status, suggesting broad accessibility and relevance. Conclusions: Social media interventions can effectively target gender norms and violence prevention, particularly among youth. Fiction-based content may be especially powerful for shifting internal attitudes, while documentary formats better support public expression and behavior. To maximize impact, norm change campaigns should strategically sequence both formats—first shifting beliefs, then reinforcing action—while leveraging digital tools to reach diverse and often-marginalized groups.