In 2007 Peter and Paul Lunder, longtime benefactors of Colby College, promised their collection of more than 500 works of art to the Colby College Museum of Art. In it are 464 works by American masters, including John Singer Sargent, Mary Cassatt, George Inness, William Merritt Chase, Winslow Homer, Paul Manship, Edward Hopper, Georgia O'Keeffe, Donald Judd, Sol LeWitt, and Jenny Holzer. Central to the collection are more than 200 prints by James McNeill Whistler, the largest single collection of art by Whistler to be given to an American academic museum. The Lunder Collection also encompasses the Colville Collection of Early Chinese Art.

More than 50 works from the Lunder gift are currently on view in the museum. In summer 2009, as the museum celebrates its 50th anniversary, additional works from the gift will be on view. In 2013 the museum will open a new wing with galleries dedicated to the permanent display of works from the collection, including the art of James McNeill Whistler.

Highlights from the Lunder Collection of paintings include John La Farge's hauntingly beautiful Agathon to Erosanthe, from 1861, one of only two paintings by the artist depicting flower wreaths; three majestic Hudson River landscapes by Sanford Robinson Gifford, painted between 1864 and 1878; the American Tonalist Thomas Wilmer Dewing's ethereal The Song, of 1891; George Inness's Spirit of Autumn, from 1891, in which the central foliage of the landscape is set ablaze by the artist’s fiery palette and brushwork; and Georgia O'Keeffe’s Birch and Pine Trees—Pink, from 1925, an important example of the artist's exploration of the abstract potential of forms within the natural landscape.

The Lunder Collection is also notably strong in American sculpture, with five bronzes each by Paul Manship (dating from 1912 to 1926) and Augustus Saint-Gaudens (from 1879 to 1904), four works by Elie Nadelman (from 1910 to 1928), two Alexander Calders (1945 and 1946), a meter box by Donald Judd (1977), one sculpture each by John Chamberlain and Claes Oldenburg (both from 1977), two kinetic sculptures by George Rickey (1975 and 1977), a sculpture of found metal by Deborah Butterfield (1987), and the first of Jenny Holzer's now-signature engraved benches (1986).