The primary purpose of St. John's College is to aid personal growth through education. St. John's College is a community of persons, students, administrators, faculty and staff, all brothers and sisters before God. Each member of this community should show concern for the others’ personal development, encouraging, stimulating, guiding and supporting one another so that each utilizes his/her talents and realizes his/her destiny as a free, creative, self-disciplined and responsible human being.

While every member of the community is important, the primary emphasis, as in all schools, is on the development of the students. St. John's College is privileged to share with parents and guardians the task of helping Belizeans attain a healthy maturity as integrated persons, Christian in their values and their vision of reality. Within the scope of its resources, it hopes to provide learning experiences which will encourage each person to develop, in an integrated way, all his/her faculties and talents -- for his/her own self-worth and to be of greater service to his/her family, the Diocese of Belize City and Belmopan, the Christian community at large, Belize and the World. The College fulfills its purpose by means appropriate to a school: personal witness, teaching and research, by the discovery, preservation and communication of knowledge and truth.

St. John's College affirms its commitment to the vision and values of the Roman Catholic Church and of the Society of Jesus, by whose members it was founded. It affirms its dedication to the people of Belize, and strives to encourage a deeper understanding of and respect for their history and culture. And finally, it strives to broaden our vision and concern to include all our brothers and sisters around the world, especially those who are poor and struggling to find that freedom in Christ which alone can bring peace to the human heart.