PROMS ARE BACK, formals are in and as parents of this year's high graduates all know, alcohol will be around in abundance -- poised to kill a celebrant somewhere. Today as a year ago, drunk driving is the No. 1 killer and crippler of teen-agers; and now as then, there is an impressive coalition of local organizations and individuals working with this region's estimated 60,000 graduating students to keep the drinkers from driving. But guess who's being reminded more than ever of their roles and responsibilities during this season?

Parents. True, it's the drunken driver under 21 who is inviting death -- and who is being killed at faster rate than anyone else. But not enough parents have been addressing this issue forthrightly. The intent of this year's "Project Graduation" being conducted by the Washington Regional Alcohol Program is not to get parents preaching to their youngsters but to set some standards, to obey the laws and to appeal to the maturity of young adults to "have a good time but to play it smart."

Parents and guardians shouldn't have to be reminded not to serve those who are under the legal drinking age in their jurisdictions; it's illegal. But society still invites drinking, and too many hosts and hostesses think it's "cute" to push drinks all around for the graduates. But even if there are legal drinkers on the guest list and alcohol on the beverage list, at least a parent or responsible adult should be on hand to keep drinkers from driving.

For assistance, the project this year includes distribution of a new brochure urging parents of teen- agers to "Be a Party to a Safe Graduation." Copies may be obtained through area schools, PTAs and service organizations or by calling GEICO, at 986- 2911. Other reminders and a list of free transportation services will be placed in tuxedo pockets by many formal-wear shops, in corsage boxes by florists and in cap-and-gown rentals.

Whatever else the graduates may have learned, they should know that there is nothing clever, grown-up, "awesome" or cool about driving after drinking. At this grand time in life, who needs grief? The posters tell it: A good friend doesn't let a friend drive drunk.