An interesting piece of research from Case Western Reserve School of Medicine suggests that students who completed an abstinence-only sex education showed an increase in "their HIV/STD knowledge, their personal beliefs about the importance of abstinence and their intentions to remain abstinent in the near future."

That’s a good thing, right? Not so fast. Abstinence-only education changed what students said about abstinence. But it didn’t make them any more abstinent—and worse, it may have encouraged a slight increase in risky sexual activity.

…the program did not affect students’ avoidance of risky sexual situations. In fact, female students and students already sexually inexperienced reported a decrease in their intent to use condoms.

The study also found the program did not significantly reduce the likelihood the teenagers would engage in sexual intercourse or to use a condom consistently.

Just another example in which actual results trump good intentions.