Though some Catholics saw room in that language for admitting celibate gay men, the Vatican followed up in 2008 with a clarification. “It is not enough to be sure that he is capable of abstaining from genital activity,” ruled the Vatican’s Congregation for Catholic Education, which issued the initial guidelines. “It is also necessary to evaluate his sexual orientation.”

Image The screenings could be “very intrusive,” said Msgr. Stephen Rossetti of Catholic University. Credit... Stephen Crowley/The New York Times

Some seminary directors were baffled by the word “orientation,” said Thomas G. Plante, a psychologist and the director of the Spirituality and Health Institute at Santa Clara University, who screens seminary candidates for several dioceses in California and nationwide.

Could a psychologically mature gay person, committed to celibacy, never become a priest? Dr. Plante said several admissions officers asked. Could the church afford to turn away good candidates in the midst of a critical priest shortage?

The Vatican permits every bishop and leader of a religious order to make those decisions, which vary from stricter to more liberal interpretations of the rules. But the methods of reaching them have become increasingly standard, experts say.

Msgr. Stephen Rossetti, a psychologist at Catholic University who has screened seminarians and once headed a treatment center for abusive priests, said the screening could be “very intrusive.” But he added, “We are looking for two basic qualities: the absence of pathology and the presence of health.”

To that end, most candidates are likely to be asked not only about past sexual activities but also about masturbation fantasies, consumption of alcohol, relationships with parents and the causes of romantic breakups. All must take H.I.V. tests and complete written exams like the 567-question Minnesota Multiphasic Personality Inventory, which screens for, among other things, depression, paranoia and gender confusion. In another test, candidates must submit sketches of anatomically correct human figures.

In interviews by psychologists  who are usually selected because they are Catholic therapists with religious views matching those of the local church leadership  candidates are also likely to be asked about their strategies for managing sexual desire.