(FORTUNE Small Business) – Caroline Gray, 13 Serial entrepreneur Wellesley, Mass.

I STARTED MY FIRST BUSINESS when I was just 10. My parents don't believe in allowances, and my sister had already locked up all the good babysitting jobs in the neighborhood. I needed money, so I decided to set up a car wash. I made a sandwich-board sign and walked around the neighborhood for an hour. When I got home, there were six cars lined up outside my house. I had to hire some of my friends to help. That presented my first management challenge: Nobody wanted to vacuum under the kids' car seats. But I made good money—about $150.

My most successful business was making stress balls that kids could squeeze. We were entering a testing period at school, and everyone was stressed out. I made my own stress balls out of colored balloons filled with flour, and sold them for $1 apiece. I sold 90 in two days.

Now all of my friends want to start their own businesses too, because it is so much cooler than bagging groceries or cleaning tables at a restaurant. Plus, you make lots more money! Last summer, among all my businesses, I made about $800. Being an entrepreneur is a perfect equation: Fun plus money plus happy customers equals a great job.

SCHOOL'S IN Number of American colleges and universities with entrepreneurship departments

2000 7

2005 19

SOURCE: Kauffman Foundation (kauffman.org)

Number of students ages 13 to 18 who participated in entrepreneurship programs from the National Foundation for Teaching Entrepreneurship

1995: 2,600

2006: 15,970

70.9%

Percentage of kids ages 13 to 18 who would like to be entrepreneurs (2006)

SOURCE: Junior Achievement (ja.org)

As Told to Patricia B. Gray (Caroline's Mother) contributed to this article.