It happens every spring. One Harvard student approaches another, asks what he's doing for the summer, and then says that he just landed a job paying $800 a month. And, incredibly, the company that hired him is looking for other students--students just like the guy who hasn't found a summer job and is getting desperate.

Sooner or later, the details emerge. The company is Southwestern Publishing, the job is selling dictionaries and encyclopedias door-to-door in the Southwest, and the salary is non-existent. The pay is through commissions, and Southwestern makes no guarantees. Nor do they pay any of the salesmen's expenses.

The company trains the salesmen in Nashville for a week or so early in the summer, and then dispatches them to places like Tuscon, Phoenix and Albuquerque to sell. The training apparently works, because the average summer earnings for the one who stick it out are very high--usually well over $2000 after expenses.

The problem, as far as the Harvard administration is concerned, is that most students who sign on with Southwestern find out the details of the job later rather than sooner.

The posters and newspaper ads naturally mention the $800-a-month pay, but don't mention the commission angle or the 12- to 18-hour days, six days a week.

The salesmen have no choice of territory--Southwestern simply tells them where to go, and tells them to sell hard.

Some Southwestern veterans also balk at selling the books, which they believe are of questionable educational value, in low-income neighborhoods where the people they are selling to may not be able to afford them.

This year, the annual cat-and-mouse game between the Harvard administration and the Southwestern people here has taken on a new twist. Harvard's own Southwestern veterans are telephoning other Harvard students and trying to recruit them.

The recruiting is not entirely altruistic. The more students a veteran recruits, the higher his "managerial" commission from Southwestern will be this summer.

The recruiter's financial incentive is the reason Archie C. Epps III, dean of students, banned Southwestern from soliciting on the Harvard campus two years ago and the reason he will summon a couple of Southwestern salesmen to his office next week.

Nobody is certain what will come from those meetings, but it appears likely that the mysterious phone calls from strangers boasting of their summer salaries will end.