September 1932: OLSH Academy opened its doors to 18 girls in the 9th and 10th grades who aspired to join the Felician Sisters.
1935: Six young women become the first graduates of OLSH.
1940s & 1950s: OLSH Academy admitted young women as day students and boarding students and lifted the requirement that the young women had to intend to become Sisters. Enrollment during this period grew from 30 to 80 students. Also during this time, OLSH added 6th, 7th, and 8th grades to the school. When St. Joseph School in Coraopolis opened, OLSH went back to offering classes to the 9th through 12th grades.
1960s: OLSH began gradually phasing out the aspirancy and the boarding facilities, which were on the third floor. Enrollment reached 100 students, and positioned OLSH for a new era.
1970: OLSH Academy became OLSH High School, and under the direction of Sr. M. Pulcheria Saukaitis '39 and the implementation of Sr. M. Augustine Grajewski '36, OLSH began to educate boys and girls, becoming co-educational.
1979: The Pennsylvania Supreme Court upheld a ruling which required public school districts to provide local bus transportation for private school students. This ruling allowed and continues to allow local students bus transportation to OLSH.
1980: Enrollment climbed to 200 students, and the 6-day cycle was established. Our Lady's Pantry was created to help feed the hungry in Coraopolis and neighboring communities.
1982: The auditorium was destroyed by fire and then rebuilt.
1985: OLSH broke ground for the Angela Activities Center and moved the gymnasium out of the main school building.
1990s: Enrollment continued to flourish, reaching 300 students, and OLSH started showing the Channel One news program.
1993: OLSH students first attended World Youth Day in Denver.
1994: OLSH earned its first accreditation from the Middle States Association of College and Schools, and the Youthtowne Young Scholars Program was established to provide a cost-free education to selected young women at OLSH.
2001: Students who participate in the Girls Hope Program began attending OLSH, first from the Clinton house and later from a new house built on the OLSH campus.
2003: A total, environmentally-friendly renovation of OLSH and the provincial house was completed. Students spent six months in temporary classrooms at the former Boyd School on University Boulevard while OLSH was under construction. The new building earned a gold LEED rating for its green features. The Tisch Family Library, an inter-generational space, opened in the new school, lending opportunities for the students and Sisters to interact.
2008: OLSH adopted the President/Principal model of governance, and Elizabeth Santillo was named its first president. That year also saw Woodcrest Residence, an apartment building for older adults, open on campus in a newly renovated, green building, the former St. Joseph Hall.
2010: A renovation and expansion project was completed at the Angela Activities Center. This project was the final piece in making the entire campus green. The new AAC seats 625 people, has two gym spaces, four locker rooms, the Michael McDonald Weight Room, two classrooms, an office suite, a concession stand, and the Sister Mary Christopher Moore Cafe.
2012: OLSH welcomed its largest freshman class and enrollment totaled 380 students under the leadership of president Terry O'Rourke Donoghue and principal Tim Plocinik.
2014: OLSH was named a Catholic Honor Roll School of Excellence by the Cardinal Newman Society.
2018-2019: OLSH won three WPIAL Championships in one year - Football, Boys Basketball, and Girls Basketball - only the third school in WPIAL history to win those three championships in the same year. Additionally that year, the OLSH Spring Musical won the Gene Kelly Award for Excellence in High School Musical Theater for Best Musical. Each of these wins was the first ever for their respective programs.