Roman Catholic secondary schools, once the stepchildren of American education, are healthy, academically rigorous and far more likely to send students to college than are public schools, a group of national Catholic educators reported yesterday.

In the most extensive demographic report ever on Catholic high schools, the National Catholic Education Association, funded by the independent Ford Foundation, dispelled a number of myths about Catholic education. In particular, it attacked the argument that Catholic schools are highly selective and thus more capable than the public schools of creating an environment for success.

The report "will be good news to many -- particularly educators whose memories stretch back to the 1960s," the study said, "when Catholic high schools were popularly viewed as second-class, second-rate, and a pale copy of what good education was all about."

The 254-page report, "The Catholic High School: A National Profile," surveyed the nation's 1,464 Catholic high schools, responsible for educating 800,000 students, and found that Catholic high school students are nearly twice as likely as public school students to enroll in college preparatory programs or to take a third year of a language.

In addition, the study said that the average Catholic high school student takes 4 1/2 years of English, 3 1/2 years of religion, 3 years of history or social sciences, 2 1/2 years of mathematics, 2 years of science, 1 1/3 years of foreign language and one-half year of fine arts.

Despite the overall robust portrait, the study pointed up some weak spots in Catholic education. The average starting salary of a beginning Catholic teacher, for example, is $11,121 compared to $14,045 for a new public school teacher. Not surprisingly, the turnover rate among Catholic school teachers is high. Fifty-four percent of Catholic high school teachers have five years of experience or less, the study said, compared to 8 percent of the teachers in public schools.

Education of handicapped students "is not a high priority in most Catholic high schools," the study found, and fine arts "appears to be a low priority."

Although careful not to draw direct comparisons between Catholic and public high schools, the report said that "the indictment of American secondary education" contained in several critical national studies "does not appear to apply to Catholic schools."

Actual academic achievement of Catholic students, which was not documented in the report released yesterday, is to be analyzed in the second part of the study next year.

In addition to the academic portrait, the study chronicled massive changes in the teaching staff of Catholic schools. In 1962, 69 percent of Catholic schoolteachers were priests, brothers or sisters. Today, clerics account for only 23 percent of the faculty.

Study participants denounced the argument that Catholic schools do not face the same economic and social problems as public schools because they draw only from elite families.

About one-third of Catholic high school students come from families with annual incomes below $20,000, the study said.

Slightly more than 16 percent of Catholic school seniors are minorities, compared to 22 percent of seniors in public school.

"It's a mistake . . . to say public schools accept everyone who comes and private schools accept only those people they want to accept," said Michael J. Guerra, associate project director.