Father Carroll ministered to the spiritual needs of the people in a wide area of Maryland and Virginia, sometimes covering over 50 to 60 miles on horseback, until he moved to Baltimore in late 1786. Three years later he was consecrated the first bishop in the United States, and in 1791 the entire Diocese of Baltimore was placed under his jurisdiction. It is important to note that the Diocese at this time covered the area that is presently half of Canada and three-quarters of the United States. The job was so vast that Bishop Carroll and the suffragan priests campaigned to have the Diocese of Baltimore divided. On April 8, 1808, Pope Pius VII named the four suffragan Sees as Baltimore, Boston, New York, Philadelphia and Bardstown. Three years later John Carroll was invested as the Archbishop of Baltimore.

John Carroll accomplished much during his lifetime. He founded Georgetown University, assisted the Poor Clares in founding Georgetown Visitation Convent, and encouraged Elizabeth Seton to found the first distinctly American congregation of religious women, the Daughters of Charity.

After Fr. Carroll left St. John’s parish, Jesuit missionaries attended to it until 1813, when it was made a mission church of the newly formed St. Mary’s parish in Rockville.  In 1850 a new chapel was built to replace the former deteriorated one and, at this time, the building officially became St. John’s Church.

At this time, Father Charles Rosensteel was pastor of St. Mary's in Rockville.   As such, he was in charge of the mission church of St. John’s.  Because of its connection to Archbishop Carroll, Fr. Rosensteel was intensely interested in the parish and, in 1893, he began construction of a new stone church near the chapel.  Construction was completed a year later and Fr. Rosensteel was appointed as the pastor, becoming the second resident pastor of the parish.

During his 38 years of service as pastor, Fr. Rosensteel had a rectory built in 1899 and a replica of the Carroll Chapel in 1906. He also rebuilt St. Peter's Church in Olney, built the first Kensington Church of the Holy Redeemer, and began a mission at Brightwood, which became Nativity Church on Georgia Avenue in Washington, DC. As a country pastor, he cared for parishioners over a widely scattered area. He was the first priest in the Archdiocese to operate a motorcycle and the second to drive an automobile in the discharge of his ministry.

Fr. Rosensteel long dreamed of building a school for the children of the parish; in 1931, he established a separate fund for this purpose.  Although the school was not built during his lifetime, he should be given credit for founding St. John the Evangelist School.

Fr. Rosensteel donated two lots to the Knights of Columbus for the construction of a new Council home in Silver Spring. In 1934, the name of the Council was officially changed to the Fr. Rosensteel Council in honor of its first chaplain. Fr. Rosensteel was the pastor of St. John's until his 80th year. He retired in 1936, and Fr. Joseph T. Kennedy was selected to be the third pastor of St. John's. Fr. Rostensteel left Forest Glen in April, 1939, because of failing health, and died on June 13, 1940 at the age of 86. He is buried in the cemetery that surrounds the Chapel, the Forest Glen Cemetery.

Fr. Kennedy served as pastor as St. John's parish changed from countryside to well-populated suburb. In addition to establishing the mission church of St. Bernadette in 1944, he ministered to St. Bernadette's and the mission church of Holy Redeemer, until they were made separate parishes in 1948.

Fr. Kennedy continued with plans to build a parish school, but St. John's parish did not own enough property to build a school in Forest Glen. He purchased the McKeever property at 10501 Georgia Avenue, consisting of 8.8 acres. The McKeever residence was used as a chapel for a short time. The school was built and opened in 1950 under the guidance and instruction of the Sisters, Servants of the Immaculate Heart of Mary. The first principal was Mother Mary Amata. It consisted of 10 classrooms and an auditorium that was under construction. When completed the auditorium doubled as a church and parish hall, and the McKeever house served as the convent. Two additions were made to the school, until it reached its current size of 16 classrooms, a library, school offices, and auditorium. Enrollment reached a high of 1,070 students in 1957. The parish celebrated the school's 50th anniversary in 2000.

The parish continued to grow in numbers even though other parishes were partially created from it. St. Catherine Laboure became a parish in 1951 and St. Andrew's was established in 1959. On May 27, 1962, His Excellency Archbishop Patrick A. O'Boyle blessed the new convent and solemnly dedicated the new Church. A large marble mosaic featuring the Crucifixion scene wraps around the front of the church and can be seen from Georgia Avenue. After completion of the rectory on Georgia Avenue, all parish life centered there. The church at Forest Glen was given the nickname the "Old Church" by the parishioners, although it is officially known as "Historic St. John's."

In 1968, Msgr. Kennedy retired as Pastor and lived at St. John's as Pastor Emeritus. Msgr. Kennedy died on his 80th birthday, January 5, 1975, and is buried at Gate of Heaven Cemetery.