Crystal Kirgiss teaches writing at Purdue University and is the author or co-author of more than ten books, including What's Up With Boys?, Sex Has A Pricetag, Girls, Guys, and A Teenager's Daily Prayer Book. She's been married to Mark, a Young Life area director, for 25 years and they have three college-aged sons. Crystal also writes the monthly "Guys" and "Girls" columns for YouthWalk magazine.