A study conducted by the National Cancer Institute showed that fifty percent more melanoma cases occurred in women ages 15 to 39 in 2004 than in 1980. The lesson here? Everyone needs to get a mole screening with a dermatologist once a year—and you should also check yourself every month, remembering to examine less-obvious places such as your scalp, the soles of your feet, and under your nails. Look at the American Academy of Dermatology's guidelines here. Even if your moles pass the test, don't underestimate the power of gut instinct: "If you look at something twice," says Philadelphia dermatologist Eric Bernstein, "show it to a dermatologist."