Peddie School is a college preparatory school in Hightstown, in Mercer County, New Jersey, United States. It is a non-denominational, coeducational boarding school located on a 280-acre (1.1-km²) campus, and serves students in the ninth through twelfth grades, plus a small post-graduate class. The school has been accredited by the Middle States Association of Colleges and Schools Commission on Secondary Schools since 1928. In its 2015 rankings, Business Insider ranked the schools tuition as the 18th most expensive private high school tuition in the United States, with tuition and fees of $44,800. The site ranked Peddie 13th on its 2015 list of the Most Elite Boarding Schools In The US, with rankings based on the size of each schools endowment, average SAT scores and selectivity. For the 2015-16 academic year, Peddie School enrolled 542 young men and women in grades 9 through post-graduate and had 79 faculty members (on an FTE basis) for a student-teacher ratio of 6:1. Peddie had 62% of students in residence. The student body represented 26 states as well as 29 foreign countries. Peddie had an average class size of 12. The senior class of 2015 was composed of 141 seniors, including 13 post-graduate students.