Just because you think "everyone else is doing it," doesn't mean they are. Some are, some aren't -- and some are lying. Of all teens under 20, about half have had sex and half have not. Most younger teens have not had sex -- only about a quarter of 15-year-olds are sexually experienced. And among teens who have had sex, most report that they wish they had waited longer to begin having sex. It's okay to delay. 

There is only one way to be 100% sure you will avoid pregnancy and STDs: don't have sex at all.

1. You can always say "no" - even if you've said yes before. Just because you have had sex with someone doesn't mean you have to have sex in every relationship after that. You don't even have to continue having sex with your current partner if you don't want to. You always have the power to say no, regardless of your sexual history or your "reputation." 
2. It only takes once. One of the most common myths among teens is that pregnancy can't happen the "first time." In fact, 20 percent of first teen pregnancies happen in the first month of sexual activity, and 50 percent of first pregnancies happen in the first six months of sexual activity. 
3. If you're drunk or high, you can't make good decisions about sex. Alcohol and/or drug use makes teens more likely to have unplanned or even unwanted sex. This leads to higher risks of HIV, STDs, and pregnancy. A survey of high school students found that 30% of boys and 18% of girls said it's OK for a boy to force sex if a girl is stoned or drunk. If you see your friends losing control, help them avoid risky situations.
4. (Teen girls) Sex won't make him yours, and a baby won't make him stay. One of the worst reasons to have sex is because you think your boyfriend will dump you if you don't. Sex and pregnancy don't guarantee a lasting, loving relationship - in fact, 80% of teen fathers don't marry the teen mothers of their children. If sex is the price of a relationship, find someone else. 
5. (For boys) Boys can say no too. You don't have to have sex to prove anything to your friends or girlfriends. Many teen boys feel pressure to have sex from their peers as well as their girlfriends, and some feel pressure to get their girlfriends pregnant. Many teen boys who have early sex say that, looking back, they wish they'd waited. Having sex does not make you a man; waiting until you're ready and acting responsibly does.
6. (For older teens) Younger teens are listening to you more than to anyone else. Talk with your little sister or brother, a neighbor, someone at school -- seek them out and let them know they can ask you anything. Kids who have positive, close relationships with their siblings are less likely to take risks with sex.
7. You’re in charge of your life. Don’t let anyone pressure you into having sex.