Holy Trinity Diocesan High School is a private, Catholic, coeducational high school founded in 1966 by the Roman Catholic Diocese of Rockville Centre.  Located in Hicksville, N.Y., Holy Trinity draws students from 62 school districts in Nassau, Suffolk, Queens and Brooklyn.

Accredited by Cognia, North Central Association and the Board of Regents of the University of the State of New York, Holy Trinity is a recipient of the National Exemplary School Award.  Admission is selective, based on the TACHS exam and 7th and 8th grade achievement.  The faculty numbers 41; 98% of whom hold a Master’s or higher degree and 40% of whom are graduates of Holy Trinity High School.