In 1959, a
David E. Finley art history fellowship took him to the
National Gallery of Art in
Washington, DC. He served as curator of contemporary art at the
Wadsworth Atheneum in
Hartford, Connecticut, from 1961 to 1968. In January 1964, he organized the show
Black White + Gray, choosing exhibits presenting what he described as "the sparse aesthetic shared by a number of artists whose work was pared down to a minimum". It is now often referred to as the first survey of Minimalist Art. In 1968, when he was not chosen for the position of museum director, Wagstaff left Hartford for the
Detroit Institute of Arts staying to 1971. In addition to his curatorial work, Wagstaff was a noted collector, just like his father, who collected
ephemera. After a conflict with the Detroit Institute of Arts' board of trustees over an
earthwork by
Michael Heizer, which had destroyed the immaculate museum lawn, he moved back to New York. After meeting
Robert Mapplethorpe in 1972 and seeing the exhibition
The Painterly Photograph, 1890-1914 at the
Metropolitan Museum of Art in 1973, Wagstaff became convinced that photographs were the most unrecognized and, possibly, the most valuable works of art. He began selling his collection of paintings, using the proceeds to buy 19th-century American, British, and French photography. Then, influenced by Mapplethorpe, Wagstaff's taste veered toward the daring, and he began to depart from established names in search of new talent. His collection was soon recognized as one of the finest private holdings in the United States. In 1984 Wagstaff's photography collection went to the
J. Paul Getty Museum, for a reported price in the neighborhood of $5 million. Saying that he needed the challenge of building another collection, Wagstaff turned to 19th-century American
silver. A show of more than 100 examples from his silver collection opened on March 20, 1987, at the
New-York Historical Society. Between 1976 and 1986, Wagstaff donated his personal papers to the Archives of American Art,
Smithsonian Institution. In 2008, the bulk of these papers were digitized and made available online (see the Samuel J. Wagstaff Papers, 1932–1985). ==Personal life==