If you’re talking to (or considering advertising to) teens on social media, you might want to adjust your strategy; there’s a new king in town. While many teens still use Facebook, their attitudes are changing quickly. They increasingly prefer alternative social media sites like Twitter and Instagram, according to Piper Jaffray’s semi-annual teen market research report. Twitter is now the hottest teen social site (26% call it their most important social site, though support has softened recently), followed closely by Instagram (23%). Facebook dropped from a high of 42% to 23%. Facebook hedged their bets last year when they acquired Instagram, so they have a pretty wide demo covered between the two. And no surprise: Instagram just started accepting paid content (read: advertising). While Facebook says they’re not worried (that teens are still using their network in very large numbers), the new info suggests taking a more nuanced approach and spreading your promotional efforts (and dollars) around.

graphic: Piper Jaffray/Huffington Post

graphic: Piper Jaffray/Huffington Post

In the same report, teens still cited “friends” as their strongest influencers for purchase decisions, though “Internet” is quickly growing as a trusted source. The social sites they rank as having the biggest impact on their purchases? Twitter, followed by Facebook and Instagram.

Colleges, time to hit the books.