A youth-driven, social media-based campaign aimed at improving knowledge about and increasing testing for sexually transmitted infections (STIs)/HIV among youth 13–17 years old was assessed by: tracking website/social media use throughout the campaign; online survey of knowledge of and attitudes towards STI testing 9 months after campaign launch; and comparing rates of STI testing at affiliated family planning clinics during the 1 year period immediately prior versus 1 year immediately after campaign launch. Over 1,500 youth were reached via social media. Survey results showed 46 % of youth had never been tested, but 70 % intended to test in the next 6 months. While the total number of GC/CT tests conducted and positive results were not significantly different pre- and post-campaign, there was a large increase in the proportion of visits at which Syphilis (5.4 vs. 18.8 %; p < 0.01) and HIV (5.4 vs. 19.0 %; p < 0.01) testing was conducted post-campaign launch. Future campaigns should incorporate lessons learned about engaging younger adolescents, social media strategies, and specific barriers to testing in this age group.