Objective: In collaboration with Residence Life, the Heads UP research team developed a 21st birthday card program to help reduce the risky drinking often associated with these celebrations. Participants: 81 students (28 males, 53 females) completed a post-21st birthday survey. Of these, 74 reported drinking during their 21st birthday and were included in the analyses. Methods: During the 2005-2006 school year, the authors assigned students celebrating 21st birthdays to either receive an alcohol risk-reduction birthday card or to a no-card condition. The students completed a survey after their birthday. Results: Students who received the card consumed fewer drinks and reached lower blood alcohol content (BAC) levels on their birthday than did students who did not receive it. Female students who received the card consumed 40% fewer drinks and reached nearly 50% lower BAC levels than women who did not receive it. Conclusion: This program is easily replicated, inexpensive, and may be used by universities to reduce risk related to celebratory alcohol consumption. (Contains 1 figure.)