At the suggestion of a group of prominent Boston physicians, Robert W. Rivers in 1915 created an open-air school for boys in Brookline; it was widely believed that the open-air concept, popular in England, promoted good health in an environment conducive to scholarship and learning. Twenty-six years and one new campus later, the Country Day School for Boys of Boston merged with Rivers. The school moved its location again, to the Loker Farm acreage—53 acres of land surrounded by conservation wetlands and a pond in Weston—in 1960. The school's Middle School program consists of grades 6-8 and the Upper School program is for students in grades 9-12.

• 433 students from 75 Massachusetts towns.
• 1:8 teacher/student ratio. Average class size: 12 students 
• 34 honors and Advanced Placement courses.
• $17.05 million endowment as of June 30, 2006.
• Graduates of 2007 are attending Harvard, Yale, Dartmouth, Wesleyan, Colby, Connecticut College, Tufts, Vanderbilt, New York University, Villanova, George Washington, Oberlin College, Notre Dame, Williams and other outstanding colleges and universities.
• In 2007, 54% of all juniors and seniors took AP exams in 15 different subjects. 91% scored 3 or above; 68% scored 4 and above; 31% scored 5.
• Eleven Rivers seniors, representing 15 percent of the Rivers graduating class of 2007, were National Merit Scholar Semi-finalists or Commended Scholars.
• In September 2003, Rivers added a unique Conservatory Program to the Upper School Program.
• Six students received honors from the 2007 Boston Globe Scholastic Art Awards competition, including one gold key, four silver keys and one honorable mention. In 2006, at the annual Small Independent School Art League competition, students were awarded 14 prizes. Seven students won first prize, three were awarded second prize, and four won third prize.
• In the 2006-07 school year, The Rivers Big Band captured gold medals at both the International Association for Jazz Education (IAJE) Northeast District Festival and at the IAJE State Festival. One student musician received the IAJE’s prestigious Most Valuable Musician award for his outstanding performance on the upright bass. In addition, five Rivers students were selected to participate in the Massachusetts Music Educators Association (MMEA) Northeast District Festival and two students received all-state recommendations.
• In the past three seasons, the girls' varsity soccer team has won three consecutive New England Championships, including two in Class C and this year in Class B. In addition, the team has clinched two straight ISL titles. In 2006-2007, Rivers had six athletes named to All-New England teams including two in cross country, three in skiing and one in football. During their 2006-07 season, the Rivers varsity girls’ hockey team made it to the finals of the New England tournament. In addition, the girls' varsity ski team won the New England Class C Championship. In 2006 and 2007 the boys' varsity tennis team won the New England Class C Championship.