36 Months is a movement for healthy teen development, aimed at increasing the age of social media citizenship in Australia by 36 months, from 13 to 16 years old. Built on a singular insight: ages 13 to 16 are a critical developmental period during which social media exposure can have long-term negative effects on mental health. On May 19 we launched a policy change campaign that hit a nerve with parents as we rallied more than 138,000 petition signatures to raise the age of social media citizenship by 36 months - age13 to 16. Leveraging political back-channeling, media, celebrity, a specific and measurable task, and an easy call to action, we created a chorus of unignorable voices. On November 7 the PM announced the changes to the law. On November 28 the Senate passed the bill. In 6 months, we achieved systemic change that will improve the way young people experience those critical 36 Months.