The idea that it's difficult to get into college is just a myth except for a small group of well-known schools, according to a new study by the College Board.

In the study -- which challenges the widely held belief that gaining college admission is a highly competitive struggle among students -- the board said that 83 percent of college applications were accepted across the country in 1978. Almost every student applying to college, the study suggested, found one to attend.

The report said that the admissions process now is becoming a competitive struggle among the colleges -- rather than the students -- as recruitment drives are stepped up in a static pool of high school graduates.

The new study is the first nationwide survey and analysis of college admissions practices ever conducted, College Board officials said.

During the 1970s, the study reported colleges said they generally became less selective, admitting students whom they earlier would have turned away. Campus buildings and staffs continued to expand during the decade, while the number of high school graduates stabilized and a college education became less attractive because of soaring tuition costs, particularly at private institutions.

"College admissions are often pictured as highly selective, rigid and narrowly focused on academic measures of ability and performance," said George H. Hanford, president of the College Board, which is the nation's prinicpal college admission testing agency. "This study shows that the reality differs sharply from that image in almost every important respect. . . The system as a whole is . . . much more inclusive than exclusive."

"In the late 1950s and 1960s -- and this is only partly tongue-in-cheek -- college admissions were a process where you looked through the folders and tried to find one excuse not to let somebody in," said Stephen Ivens, the board's research director. "Now you look at the folders and try to find one excuse to take the."

The study was based on information from 1,463 of the nation's approximately 2,600 accredited colleges and universities. The survey was conducted by the College Board and the American Association of Collegiate. Registrars and Admissions Officers. The information on trends comes from questions in the survey form asking colleges to compare what they were doing in 1978 with what they did in 1970.

Throughout the country only 8 percent of colleges reported that they admit a limited number of their applicants. More than a third take all high school graduates while the remaining 56 percent admit well over a majority of applicants, usually 60 to 90 percent, College Board officials said.

Overall, the colleges involved in the study had 2.25 million applications in 1978 and made 1.9 million offers of admission, producing an 83 percent acceptance rate. But because many students applied to more than one institution, only 1.3 million enrolled.

In the Washington area, the proportion of applicants accepted in 1979 by different colleges ranged from virtually 100 percent at the University of the District of Columbia and the community college in Prince George's, Montgomery, and Northern Virginia, to a low of 34 percent at Georgetown University. At the University of Virginia 41 percent of applicants were admitted, but more than 80 percent got in at the University of Maryland, George Mason University and Catholic University.

The College Board promised that none of the colleges involved in the study would be identified and the report did not name those that are highly selective. But according to the National College Databank, published by Peterson's Guides, only 70 colleges across the United States draw more than half their freshmen from the top 10 percent of their high school class. Only 26 colleges report that more than three-quarters of their freshmen scored over 600 on either the verbal or mathematics section of the Scholastic Aptitude Test.

In Washington, Maryland, and Virginia the colleges appearing on the lists are Georgetown, Johns Hopkins, St. John's College and the U.S. Naval Academy in Annapolis, and the University of Virginia.

Joseph Monte, a longtime guidance counselor at Einstein High School in Kensington, said the new College Board study confirms a trend that high school counselors have seen over the last decade.

"The number of schools that are requiring achievement tests is way down," said Monte, who is a former president of the National Association of College Admissions Counsellors. "A great many schools, even Yale, are telling their good applicants early if they've been accepted so they don't lose them to someplace else. Even many of the public institutions that would never do recruiting out of state now are inviting [guidance] counselors from around the country to their campuses so they can keep a national student body."

Both Monte and Ivens added that one other factor in the decline in selectivity by colleges is the apparent increase in "self-selection" by students before they apply.

Monte said high school counselors are becoming more sophisticated in telling students where they are likely to be admitted, while Ivens said the colleges are putting out more detailed information of what kind of students they have accepted in the past. "Students are being more realistic," he said.

As a result of self-selection by potential students, Ivens continued, acceptance rates are not a fully reliable indicator of the prestige or quality of a particular institution. For example, St. John's College, which offers a Great Books program based on the classics, admitted 83 percent of its applicants in 1979, but more than two-thirds of it students had College Board scores over 600 (800 is the maximum score). At Howard University in Washington, just 51 percent of applicants were admitted, but average College Board scores were about 400.

Nationally, according to the report, 34 percent of colleges said they admitted students with lower standardized test scores in 1978 than in 1970, while only 13 percent said test scores had inproved. Some 29 percent said they required fewer courses in high school, while only 11 percent said their course requirements had stiffened.

Overall, 23 percent of colleges said they were less selective now than in 1970, compared with 18 percent that said they were more selective. Among liberal arts colleges, 32 percent said they had become less selective, while only 20 percent said they were more so.

About two-thirds of all colleges said they actively recruit academically talented students, but 58 percent said they recruited athletes and 55 percent said they recruited blacks and other minorities. Some 37 percent said they admitted minorities even though their grades, test scores and class ranks were lower than other applicants.