Since 1905, Emerson Hall has been the home of the Department of Philosophy at Harvard University. Designed by Guy Lowell, the building is named for Transcendalist writer, philosopher, and Harvard alumnus Ralph Waldo Emerson (A.B. 1821; LL.D. 1866). A bronze statue of Emerson by artist Frank Dubeneck was installed on the first floor of the building on May 25, 1905, to mark what would have been Emerson's 102nd birthday. The statue remains there today.

Emerson Hall opened for use in the middle of the 1905-06 academic year. Originally the hall contained two libraries on its second floor: Robbins Library of Philosophy—named for Reginald C. Robbins, '92, whose generous gift to the department made possible the acquisition of its original collection—and a social ethics library. Each also had its own librarian: Dr. Benjamin Rand served as the first Robbins librarian, and Dr. D. C. Rogers oversaw the social ethics library. Today, only the Robbins Library remains, but its largely unchanged interior provides a striking example of early 20th century library design.

Initially, the entirety of Emerson Hall's third floor was devoted to the Psychological Laboratory under the direction of Dr. Hugo Münsterberg. The Psychological Laboratory contained twenty-seven rooms, among which were class rooms, a photography room, a sound-proof room, various animal rooms, an instrument room, a wood-shop, and a Vivarium housing birds, monkeys, rabbits, guinea-pigs, mice, rats, frogs, turtles, and other reptiles. Today the third floor contains faculty and administrative offices as well as seminar rooms, a graduate student lounge, and a lecture hall.