Holy Trinity opened its doors in the fall of 1994. Three Sisters of Mercy, Sister Carol, Sister Terrance, and Sister Rose were on a very limited budget, however these women had lots of love and ambition. There was an extreme need at the time to provide Catholic Education to students of Cape Cod. Holy Trinity opened in tandem with Buzzards Bay based St. Margaret's School. Sister Carol believed at the time that more schools would be built in the future. In it's first year, the school went from 31 students to 82 students the following year. It originally served kindergarteners, first and second graders. The school continued to add one grade level per year. The school's success was attributed to strong education and small classroom numbers. The children are taught daily about values, justice and principles. In 2005 the decision was made to remove the middle school, grades 6-8 and to add a pre-school, creating a true elementary school. The love and nurturing learning environment established by Sister Carol will continue in the future.

The Faculty of Holy Trinity School believes that we have the responsibility to see that each student achieves his/her maximum potential, morally, socially, educationally, and emotionally. Therefore, we strive:
• To teach the Gospel of Jesus
• To live the message found in the gospel of Jesus with love and respect.
• To bring the message to life in service to others.

The purpose of education is to lead students to Christian maturity. Catholic education develops young people into whole and well-rounded individuals. We, the faculty of Holy Trinity School, believe that each of our students must have a clear understanding of the identity and dignity of every person. Therefore, we strive to provide an education that:

1. Reinforces Christian values, by helping students make independent moral decisions, based on ethical standards of behavior within a Christian learning environment, where belief in the reality of God is evident.

2. Encourages responsibility for one's behavior, open-mindedness and risk-taking; recognizes the need for, and willingness to, change; accepts those of different origin or physical well-being or gender.

3. Encourages what is good; promotes achievement, general welfare and happiness; accepts that learning by mistakes is legitimate; and encourages cooperation and a positive approach toward others, with a sense that what one does is important and makes a difference.

4. Encourages the school as community; recognizes that parents, students, teachers, administrators and other school personnel are on the same team; promotes respect for the work place and cooperation with business and industry.