The History Club screens historical movies once a quarter after school and is open to all students.

The International Club allows students in grades 10-12 to explore foreign cultures through a variety of experiences such as local field trips to festivals and museums as well as in-school cultural presentations by guest speakers, movie nights, and more.  In addition to attending events, club members take on leadership roles and fulfill social responsibilities by running club activities and holding fundraisers to support international organizations.

As the School’s premiere instrumental and vocal soloist ensemble, the Jazz Pop Ensemble performs throughout the year at three school events. The group performs in many styles. The winter season provides time to work on classic big band arrangements and popular songs. During the winter, the group prepares to perform at our annual semi-formal dance and in doing so, becomes a dance band playing songs from the 1960s through today.

The Latin Club strives to capitalize on student enthusiasm for Latin by furthering their understanding of the pervasive influence of Classics upon the community of St. Sebastian’s and the larger world. Events include movies on Classical themes, Latin Mass, field trips, guest lecturers, Certamen Night, and Classics Day at Holy Cross. 

Moderated by faculty, this club explores the fields of medicine, neuroscience, and biotechnology and provides students the opportunity to visit and conduct mock medical assessments at Harvard Medical School.

The Liturgical Ministries at St. Sebastian’s reflects a service to the school community unlike any other club. The ministries are composed of Altar Servers (for daily and monthly masses), Readers (Lectors), Eucharistic Ministers (Extraordinary Ministers of Holy Communion), the Schola (Liturgical Choir) and Mass Ensemble (Instrumentalists). This program involves both adults and students in the St. Sebastian’s community, working side by side for the greater glory of God. Membership is open to all students in grades 7-12.

Open to all seventh and eighth grade students, the Math Club meets each week to challenge interested students with advanced mathematical problems and puzzles.

Open to all students in grades 9-12, The Math Team competes in contests that are associated with the New England Mathematics League. There are six competitions per year; occasionally, students also compete in the American High School Mathematics Exam that is held once a year.

MPA exists for the purpose of exploring and continuing traditions of social and cultural exchange with particular attention focused on communities of color. The group remains faithful to the St. Sebastian’s ideals of social service and charity. MPA educates its members and the whole School, regarding a variety of racial, cultural, and religious issues as they affect individuals and the entire School community.

The Quiver is a literary and artistic magazine organized by students and faculty members of St. Sebastian’s School. The publication is produced annually and contains poems, creative essays, short stories, photography, and art produced by students.

Real Estate Club offers students of all grades an opportunity to learn about commercial and residential real estate brokerage, investments, and development and often features guest lecturers from the real estate industry.

Students in grades 7-12 work as members of a competitive team to design and develop a working robot to accomplish a given set of tasks through unstructured problem solving.

St. Sebastian's has enjoyed a special relationship with The San Miguel School in Providence, RI for several years. The independent middle school for boys is dedicated to the belief that education is the key to breaking the cycle of poverty. This service program strengthens our bonds with our San Miguel brothers and allows St. Sebastian's students to experience the Catholic nature of the universal call.

The Sports Media Club is open to students in grades 7-12, who show an interest in covering sport from a media perspective. The various media outlets that are covered in the Club are: Photography, Videography, Social Media, and Play-by-Play Announcing. Students have the ability to improve their talents by covering St. Sebastian's sporting events and hear from guest speakers. No prior experience required.

Juniors apply for this leadership opportunity to mentor younger St. Sebastian’s students on academic and social topics.

This academic journal is published twice a year and is a compilation of outstanding academic essays written by students in grades 9 through 12. A group of editors, ordinarily seniors and juniors, oversee the content and editing of The Journal in order to provide all members of the St. Sebastian’s community a window into the academic writing of our most thoughtful students.

Comprised of 15 students who are elected to office, the Student Council members organize activities and fundraisers and are available to assist at parent and school functions. The members work to bring ideas from the student body back to the Student Council and from the Student Council to the students.

SADD is a peer leadership organization dedicated to positive peer pressure, role modeling, and strategies that empower young people. Our mission is to provide students with the best prevention and intervention tools possible to deal with issues concerning healthy vs. destructive decisions.

Voces de San Sebastián is a bilingual cultural newspaper in Spanish and English, organized by students and faculty members of St. Sebastian’s School. The publication is produced every other month and features articles written by students on culture, current events, sports, food, news, and entertainment related to the Spanish speaking world.

The first issue of the school newspaper was published in February 1945, just months before the first senior class was set to graduate, and remains a valued tradition at St. Sebastian’s today. The student-run paper is published seven times a year and includes an array of articles, from school sports recaps and drama production reviews to world and pop culture news.