Ascension Catholic is the oldest Catholic school in the Diocese of Baton Rouge, and traces its origins to the arrival in Donaldsonville of six Daughters of Charity in 1845. At the time, all of the United States was part of the Archdiocese of Baltimore, Maryland. In 1850--the same year that New Orleans became the second archdiocese in the United States--a large three-story brick convent building was constructed in Donaldsonville to serve as a hospital, school(originally known as St. Vincent Institute), and residence for the Daughters of Charity. In 1854 this convent building also became an orphanagefor children whose parents were killed by yellow fever. That 1853 epidemic killed more than 10,000 in the greater New Orleans area. In 1885, the Sisters of the Holy Family came to Donaldsonville and started St. Augustine School for African American children. In 1886, the Brothers of the Sacred Heart came to Donaldsonville to start a school for boys named St. Joseph Commercial Institute. With the establishment of St. Catherine Parish in 1924, St. Augustine School was renamed St. Catherine School. St. Joseph Commercial Institute became known as Catholic High School in 1930. In 1954 new high school facilities costing $238,000 were built for the high school divisions of St. Vincent Institute and Catholic High School.
In 1961 a new convent building costing $132,000 was built for the residence of the Daughters of Charity, and the 1850 convent was entirely used to house the elementary division of St. Vincent Institute. The high school division of St. Catherine School merged with St. Vincent Institute and Catholic High School in 1965, and in 1969, all three original schools merged to become Ascension Catholic Interparochial Schools. The 1850 convent building housed the elementary division and the St. Catherine School campus housed the middle school division. Between 1969 and 1975, $439,000 would be spent to build a new classroom wing at the middle school campus, a new classroom wing at the elementary school campus, and a new Administration building and library building at the high school campus.
| 1845 | January 1, 5:30 am., The Sisters of Charity of St. Joseph arrived from Emmittsburg, Maryland to open St. Vincent's Institute. |
| 1850 | The Sisters of Charity of St. Joseph became the Daughters of Charity of St. Vincent de Paul. The Old Convent building was completed to serve as a hospital. |
| 1861 | Hospital closed due to lack of funding — 13 orphans accepted. |
| 1862 | Federal troops took New Orleans and bombarded and burned Donaldsonville. Orphans were given refuge in the Sacred Heart Convent when St. Vincent's Institute was threatened to be burned. Sgt. Scott, who killed the Union Lieutenant who ordered it burned, saved the building, but was later executed for his act. |
| 1885 | The Sisters of the Holy Family opened St. Augustine's School for Black children. |
| 1887 | December 20, The Brothers of the Sacred Heart opened St. Joseph Commercial Institute for boys located on Paradise Alley. |
| 1894 | St. Joseph Commercial Institute was chartered as an institute with power to grant degrees. |
| 1929 | Football team was in existence. |
| 1930 | St. Joseph Commercial Institute became Catholic High School. |
| 1931 | St Marie Fogerty assigned to St. Vincent Institute. |
| 1941 | Football team was State Champs. |
| 1942 | St. Augustine's School was renamed St. Catherine School. |
| 1953 | School band established. |
| 1955 | Ascension Catholic High School built. St. Vincent's Institute was on one wing and Catholic High School was on the other wing. |
| 1961 | New convent completed for Daughters of Charity. |
| 1963 | Catholic High School discontinued boarding students. |
| 1964 | The Daughters of Charity exchanged their traditional habits with the white coronet for a more practical dress. |
| 1965 | St. Catherine High School was dosed; the students were allowed to transfer to Ascension Catholic with grades 5-8 housed at St. Catherine, renamed ACMS. |
| 1968 | The Brothers of the Sacred Heart departed. |
| 1969 | All three schools, St. Vincent's, Ascension Catholic Middle, and Catholic High School were amalgamated into Ascension Catholic Interparochial School to serve 14 church parishes. The schools were under the direction of the Daughters of Charity assisted by the Sisters of the Holy Family. |
| 1970 | Catholic High School (old rectory) burned. |
| 1969-1975 | Ascension Catholic Primary school built 11 new classrooms, but they continued to use space in the St. Vincent Institute building (built in 1850). Four new classrooms were built at Ascension Catholic Middle School, and a new administration building, library and class rooms were built at Ascension Catholic High School. |
| 1973 | Football team was State Champs. |
| 1977 | Ascension Catholic High School was accredited by Southern Association of Colleges and Schools. |
| 1978 | St Natalie Marengo awarded prize in national contest by Scholastic Magazine. |
| 1980 | ACIS Development Program was established with a major fund raising drive. |
| 1981 | Sr. Marie Fogerty died in January The Sisters of the Holy Family withdrew in June. |
| 1987 | The Daughters of Charity of St. Vincent de Paul withdrew. |
| 1992 | Football team was State Champs. |
| 1993 | Baseball team was State Champs. |
| 1994 | Baseball team was State Champs. Blue Ribbon Committee reactivates the ACIS Development Program. |
| 1995 | 150 year anniversary "The Tradition Continues" Ground Breaking Ceremony 9/11/2001 – America was changed forever…. Terrorist attack World Trade Center and the Pentagon 2004 Groundbreaking for new Science Lab and Computer Labs on the High School Campus |
| 2005 | Danceteam places 1st in the National Danceteam competition in Orlando, FL |
| 2005 | Hurricanes Katrina and Rita devastated the New Orleans area. Ascension Catholic took in over 200 new displaced students from the New Orleans area |
| 2006 | Marie U. Fontana, Founder of the Ascension Catholic Alumni Association died on April 28, 2006. Alumni Association was founded in 1983. |
| 2008 | Renovation and dedication of four classrooms on the second floor of the "old convent" |
| 2008-09 | Consolidation of Middle School with the Primary and High School campuses |
