The first Catholic high school in the Diocese of Brooklyn was St. James Academy on Jay Street, established circa 1869. It had two divisions, one for boys, one for girls. Both divisions were originally two-year high schools (the standard in education through the 1920s) with the option of continuing further studies at the school in order to obtain training as a teacher. Many of the teaching Brothers and Sisters in the diocese attended St. James Teaching Academy, one of the first NYS accredited teaching schools.

During the early years of the diocese through circa 1930, most of its high schools were associated with its parishes and offered a two-year course of study. These included parish high schools at Holy Name, St. Bartholomew, St. Barbara, St. Brendan, Queen of All Saints, St. Aloysius, Most Holy Trinity, St. Saviour, St. Michael for Boys, East New York, All Saints, St. Francis Xavier Commercial, St. Thomas Aquinas, St. Michael Diocesan for Boys, Bay Ridge, St. Teresa, Sterling Place, Holy Rosary, St, Augustine, St. James, St. Stephen, and St. Catherine of Alexandria. Later parish high schools were established at St. Pascal, St. Michael for Girls, East New York, OLPH, Our Lady of Wisdom, St. Edmund.

The parish high schools were mainly two-year schools. Initially, during the early part of the 20th century, both girls and girls would go to work after two years of commercial high school study. St. James Academy and St. Thomas Aquinas Academy offered teacher-training schools. In 1926 when Bishop Molloy announced the opening of The Bishop McDonnell Memorial High School for Girls, the pastors of most of these two-year girls high schools were asked to close their schools and send their students to the new Bishop McDonnell. Monsignor Charles Vitta who had founded Holy Name High School for Girls at the Park Slope parish of the same name, initially refused to close his high school and asked permission instead to expand the school, which was staffed by the Sisters of St. Joseph, to become a four-year Academy for girls.

The Bishop would not approve this plan and Holy Name, along with most of the other girls parish high schools, was forced to close in deference to Bishop McDonnell. Queen of All Saints was permitted to remain open, although all students were transferred to Bishop McDonnell after they had finished two years. All Saints, St. Brendan, and St. Saviour were permitted to stay in operation and expanded to four-year schools. St. Bartholomew and St. Barbara also remained open, while St. Michael's East New York changed its focus from boys to girls.

Bishop McDonnell Memorial HIgh School was located at 260 Eastern Parkway, 'Bishop's,' as it was known, had an enrollment of nearly 2,000 girls and offered both academic and commercial courses of study. The students did not wear uniforms, rather they arrived to school in what would today be considered formal business clothes, or at least high end casual. Bishops was unique in that it was the only school in the diocese that was staffed by five different congregations of women religious. These were the Sisters of St. Joseph, Brentwood, Sisters of St. Dominic, Amityville, Daughters of Wisdom, Sisters of Mercy, Brooklyn and Sisters of Charity. Bishop's provided the diocese with hundreds of vocations to these different Congregations. In 1948, the Sisters of St. Joseph opened The Bishop McDonnell Memorial Annex at their former motherhouse in Flushing. "The Annex" as it was known housed an average of 400 additional Memorialites."

More than 1100 vocations came from among the graduates of Bishop McDonnell.

In 1926, St. James Academy for Boys was renamed Bishop Loughlin Memorial High School for Boys in honor of John Loughlin, the first Roman Catholic Bishop of Brooklyn. In 1933 the school moved from Jay Street to Clermont Ave. Though now co-ed, Loughlin is the only one of the three original diocesan high schools for boys still in operation. The other two were St. Augustine's and St. Michael's, Bay Ridge. Today Loughlin houses the official alumnae centers for both Bishop McDonnell Memorial High School and St. Augustine High School. St. Michael's Boys High School became Xaverian High School and moved to Ft. Hamilton.

Two of Brooklyn's most famous boys high schools were Brooklyn Prep, conducted by the Jesuits and located in Crown Heights and St. Francis Prep, conducted by the Fransiscans. People often forget that St. Francis actually had two Brooklyn locations. The original school was located on Baltic St. (with buildings on Butler St.) before moving to N.6th Street. St. Francis Prep became a coeducational school when it moved to its present location in Fresh Meadows, Queens in 1974. It is the nation's largest Catholic high school. Brooklyn Prep was long considered the bastion of boys Catholic high schools, both in academics and athletics, and maintains an alumnae website that is open only to graduates of the school.

Most Holy Trinity Boys High School was part of Most Holy Trinity parish in Williamsburgh and was opened as a German parish high school. Its "sister school" was nearby All Saints Commercial High School which was conducted by the Amityville Dominicans. Both schools were shuttered in the early 1970s. The Dominican Sisters of Amityville also operated St. Nicholas Commercial High School and St. Michael's Commercial High School, both parish high schools that also closed in the early 1970s.

The college prep high schools for girls of the Diocese of Brooklyn have always been far stronger academically than those of any other diocese. Almost all of the girls schools have been owned and operated by individual Congregations of Women Religious. St. Agnes Seminary, founded in 1878 in what was once called Madison Gardens but now known as Flatbush, was one of the earliest college preparatory girls high schools in Brooklyn, along with St. Francis Xavier High School founded in 1887 on Carroll Street. St. Angela Hall founded in 1908 in Brooklyn, was a unique girls high school in that it offered a four-year program with an emphasis on the Fine Arts. St. Francis Xavier, beloved home to the "Xavierites,' closed in 1962 when the diocese opened six new regional high schools, St. Agnes closed in 1977 and St. Angela Hall fell silent in 1980.All three academies were conducted by the Sisters of St. Joseph.

At a time when most women were relegated to administrative and secretarial positions, the Commercial Catholic high schools of the Diocese of Brooklyn prepared young women for full-time work upon graduation. St. Joseph Commercial High School. All Saints, St. Michael, St. Nicholas, and, of course, Dominican Commercial, all operated at a level of the professional business schools of the day. Their graduates were eagerly sought by some of the largest and finest companies in New York City and beyond. While the Sisters of St. Joseph were the leaders in college preparatory academies, the Sisters of St. Dominic administered the most widely respected commercial high schools in the entire metropolitan area, as well as the Kaupert Secretarial School.

Two Brooklyn schools about which Piro could find very little information are Euphrasian High School for Girls and St. Leonard's High School for Boys. Not one person with whom she spoke, even in the diocesan offices, could recall either school, although they are both listed in the Catholic Directory as high schools in Brooklyn.

Many forget that the Diocese of Brooklyn was also home to several novitiate high schools, called Juniorates, (Generalates were located at a congregation's motherhouse) for the various Congregations of Women and Men Religious of the diocese. These included the Mercy Juniorate, the Dominican Juniorate, the Josephite Juniorate, the Sisters of the Good Shepherd Juniorate, the Franciscan Brothers Juniorate (also in Smithtown,) and the Jesuit Juniorate. The Juniorates provided a high school education coupled with vocation development and guidance. Most of the Juniorates were closed in the 1950s and early 1960s. Brooklyn was also home to the original Cathedral Prep Seminary before its move to Elmhurst, Queens.

In 1960, as a response to the burgeoning enrollment in Catholic elementary schools, the Diocese of Brooklyn announced plans to build six state-of-the-art diocesan high schools large enough to house the number of Catholic baby boomers reaching high school age. Fundraising began throughout the diocese and the schools opened in 1962. These included, in Brooklyn, Bishop Ford, Nazareth, and Bishop Kearney, in Queens, Christ the King, Mater Christi and Bishop Reilly. Bishop Ford, Christ the King and Bishop Reilly were co-institutional, meaning that the school housed both boys and girls, but they were in separate areas of the school building and classes were single-gender.

Unfortunately, maintaining these diocesan schools proved too much of a financial burden for the Bishop's office, especially in light of the declining population of Catholics of high school age, and after approximately ten years, the diocese was forced to close, sell or consolidated most of these schools.

St. John's Prep, which is now located in the building that once was Mater Christi High School, began as part of St. John's College/University on Lewis Ave. in Brooklyn. For nearly 52 years, the high school division was housed within the same building as the college. No distinction was made among the students as to who was in secondary school and who was in college until the student's fourth year of study.

A separate high school building for St. John's Prep was built in 1927 and dedicated Moore Memorial Building. St. John's Preparatory High School was officially established at this point. When St. John's University made the move to Hillcrest, Queens in 1955. St. John's Prep took over several of their buildings before a changing society and financial pressures forced the high school to close. After the reorganization of Mater Christi High School in 1977 and again in 1980, St. John's Prep was reborn in its place.

"If every Catholic school graduate gave just a few dollars a year to Catholic education, it would make such a difference. Even if your particular Catholic school is no longer in operation, contributions to any Catholic school are always welcomed for scholarships which would enable so many young people to enjoy the spiritual, intellectual, social, and moral benefits of attending a Catholic school."