OVERCROWDING at Harvard and Radcliffe will again reach crisis levels this Fall, forcing most Houses to overload many suites and take other extraordinary steps. But both besieged House secretaries and a noticeably calmer Harvard Administration continue to hope the usual safety valves will relax the housing crunch.

Six river Houses have converted office space into bedrooms or added beds to sophomore suites to cope with between 17 to 40 floaters. The other three Harvard residential Houses--Adams, Lowell and Eliot--present less serious problems.

At the Quad, Currier House faces the worst situation; most freshmen there have been confined to economy suites. South and North Houses, on the other hand, only suffer crowding similar to last year's.

Many House secretaries wonder if the extreme crowding can be comfortably absorbed, but Eleanor C. Marshall, assistant to the deans of Harvard and Radcliffe and the new director of the Housing office, remains tranquil. She is optimistic the crunch will ease within several weeks.

Overcrowding is a Fall concern as inherent to Harvard as worry over the latest Coop rebate. But the extra students generally disappear within several months--upperclassmen move off campus, transfer to less crowded Houses or co-ops, or take a leave of absence.

The present crisis differs in several crucial ways from its predecessors, and the differences may bear out the pessimism of some House secretaries. A recent trend toward leave-taking, which relaxed crowding, has leveled off. Possibly it has been reversed.

SEVERAL YEARS ago John T. Dunlop, then dean of the Faculty, pressured the College to accept transfer students in order to fill spaces left by the leave-takers. Now Dean Whitlock says the crunch may prevent Harvard and Radcliffe from accepting transfers next year. All told, 38 students will transfer into both Colleges.

The small size of the class of 1973 is a major cause of the current crisis, according to Bruce Collier, who programmed the computer that made last Spring's freshmen housing assignments. Collier predicted last June that the small class meant an additional 70 students in the housing pool.

The crowding this Fall is similar to four years ago (the delayed opening of Mather House caused that crisis), but this year no major safety valve is on the horizon.

In fact, Mather, the House which alleviated the last major crisis, is now caught in the middle of the current one. Mather, whose only attraction to freshmen has been guaranteed singles for sophomores, has now moved an additional bed into every sophomore suite in order to deal with a 35 to 40 student overflow.

FRESHMEN WILL be the undergraduates who will suffer in Currier, which cannot for architectural reasons adapt as easily as Mather can to overflows. Suzanne T. Nelson, Currier House Secretary, said last week that all but three or four of Currier's 100 freshmen will begin the year in economy doubles or economy triples. In an unprecedented step, ten Currier freshmen have been assigned to Jordan W (a co-op), because, Nelson says, "I had no more beds."

Nelson said that last year's experience gave no reason to think that this year's 30-student excess will dissipate. She explained that last Fall no one took a leave of absence, so the ten economy doubles set up to deal with the "temporary" overcrowding remained intact until the Spring term.

Quincy House, which is also restricted by its architecture, has added beds to its sophomore suites--located in Quincy's old section--to cope with a 30 to 35 student overflow.

Susan A. Loth, Quincy House secretary, said last week that she had been forced this summer to refuse three late-comers housing. Loth said she believes that this year the problem will not dissappear because the number of extra people is too large.

In order to house about 25 floaters, Winthrop House has split up roommate groups and stuffed students wherever practical. The House has also converted its senior common room and guest suite into undergraduate housing units and added unaccounted-for House members to sophomore suites and some junior and junior-senior suites.