St. Isidore's Roman Catholic School 515 Marcy Ave, Riverhead, NY11901 St. Isidore's R.C. School, located on Marcy Avenue, is a private, coeducational school teaching preschoolers through…More eighth graders. The school was originally founded in 1961 to benefit the children of St. Isidore Church, on Pulaski Street. Since then, other congregations support the school, including: St. Mark in Shoreham, St. Anthony in Rocky Point, St. John the Baptist in Wading River and St. John the Evangelist in Riverhead, however acceptance to the school is not limited to parish members. Sister Linda Joseph has served as principal for the past 17 years.