Of course you don't want your child to be one of the roughly 3,500 who decide to light up daily, but how do you ensure she's not tempted to try cigs? It's all about what kids see. One recent study found that puffing movie characters - both good guys and bad guys - enticed them to pick up the habit. Pro-smoking messages are influencing kids by infiltrating the Internet, too - more than half of this content shows up on social-networking sites like MySpace. "The more children believe 'everyone else is doing it' - not just their peers but the number of people they see puffing away in general - the more likely they are to try it, too," says Michael Siegel, M.D., a professor of community health sciences at Boston University School of Public Health. Combat the bad influences by:

Hammering home the message: A recent Swedish study found that parents who repeatedly talked to their kids about not smoking made a huge, positive impact. The children were more apt to follow their parents' advice - even if they had already started smoking. Be sure to emphasize the negative impact cigarettes have on health.

Banning butts in public: Kids who live in towns that ban smoking are about 50 percent less likely to light up than those from areas without such regulations - or with very weak ones. "These laws give kids the perception that smoking is not socially acceptable, and that's a powerful deterrent," says Dr. Siegel. "It seems far less cool if you have to do it outside alone in the cold."

Teaming up: New research at Dartmouth Medical School shows that kids who play team sports are two times less apt to smoke than those who aren't on the court or playing field. Game on!