The Vatican has begun a first-ever comprehensive study of women's religious orders in the United States, four decades into a steep decline in the number of Roman Catholic sisters and nuns in the country. The study, ordered by a Vatican congregation in December and announced Friday in Washington, will examine "the quality of the life" of 59,000 members in more than 400 Catholic women's religious institutes, said Sister Eva-Maria Ackerman, a spokeswoman for the study, which is called an apostolic visitation. "The study is really to encourage the communities, to strengthen them, to help them grow in their vitality," she said, adding that "women's religious communities have played such a significant part in building up the church and society in this country." The Vatican released results of a similar canvass of US seminaries earlier this month in light of the clergy sexual abuse crisis. That review gave special attention to chastity and celibacy, and the Vatican found seminaries had largely been successful in rooting out "homosexual behavior."