This letter is to break the hard news to your family that you've decided to drop out of school.
1234, Main Street
Boston, MA 02123
09 April, 2005
<Recipient Address Goes Here>
College has been one of the most fascinating, challenging, eye-opening experiences of my young life, and I wouldn't trade the things I've learned or the people I've met for anything in the world. However...I'm dropping out. You're probably a little surprised (okay, make that a lot surprised), and I'm not going to try to explain myself in this letter. Just let me say that I've given this a lot of thought, and I've decided that I want to try my hand at <what you'd rather do> instead. It's what I want, and I hope you'll back me up. Dial 911 if you need to, and give me a call. I'll try to explain more clearly. I hope you understand that this is what I really want to do.
encl: <List of enclosed items goes here>