The Knights of Columbus, a Roman Catholic fraternal organization, has commissioned the Chicago-based National Opinion Research Center to do a comprehensive study of the religious behavior of U.S. and Canadian Catholic young people between the ages of 15 to 30.

According to Supreme Knight Virgil C. Dechant, the study, which will cost about $250,000, will focus particularly on young men's and women's attitudes toward priestly and religious vocations.

"We know that our young people are very interested in religion and prayer," Dechant said. "We also know that they seem less committed to institutional religion than in the past.

"But we do not know the reason for the dramatic decline in vocations. It is our hope that the study will provide the Church with some explanations and some answers to the vocation crisis."

Our Sunday Visitor, a national Catholic weekly, reported last year that the number of young women studying or preparing to enter the sisterhood had declined a "shocking" 90 percent since 1967.

The article also reported that the total enrollment of young men studying for the priesthood had dropped 64 percent since 1964, from 48,992 to 15,943.

In addition to the vocation problem, the study will examine the impact of various kinds of religious education and catechetical methods, the religious problems and needs of young people as they see them, and the attitudes of youth toward fraternal organizations like the Knights.