The Cat in the Hat turned 50 this month, and in celebration you can help kids read. Random House is donating a book to First Book, a non-profit that gives low-income children their first book, for every Dr. Seuss book purchased before May 7, 2007 (must send a receipt to Random House) and for every birthday card sent to the Cat in the Hat.

Random House is limiting it to 2 million books (a million for each Dr. Seuss book purchased and a million for each card received), but according to the web site they’ve already received more than 1.2 million cards. So you might need to go with the purchase a book option to make it count (or send a card anyway and see if Random House decides to go beyond their 1 million book limit).