In 1966, Gaehtgens completed his Ph.D. dissertation on the French Renaissance sculptor
Germain Pilon at the
University of Bonn. In 1972 he published his Habilitationsschrift about
Joseph-Marie Vien at the
University of Göttingen. For some years he worked as an adjunct professor at the Art History Seminar of this university. From 1979 to 1980, he spent some research time at the
Institute for Advanced Study in
Princeton, New Jersey. From 1980 until his retirement in 2006 he was Professor of Art History at the
Free University of Berlin. Soon after his appointment to Berlin's University, Gaehtgens began turning his attention to pre-twentieth-century American art, which was not a primary field for art historians at German universities at that time. In 1985–86 he was a
visiting scholar with the Getty Center for the History of Art and the Humanities. In 1988, this led to a major exhibition of American 18th- and 19th-century painting in Germany. In 1992, Gaehtgens took over the organization of the Twenty-Eighth International Congress of the History of Art in Berlin. From 1992 to 1996, Gaehtgens was president of the
Comité International d'Histoire de l'Art (CIHA), which is supported by the
Association of Art Historians. In 1997, he founded, with German, French, and Swiss colleagues, the
Deutsches Forum für Kunstgeschichte in
Paris (Centre Allemand d'Histoire de l'Art de Paris), which organizes conferences, symposia, and workshops, undertakes research projects, and has published many books on art. From 1998 to 1999 he was Chaire européenne at the
Collège de France. In 2004, he received an honorary doctorate at the
Courtauld Institute of Art,
London. In November 2007, he was appointed director of the Getty Research Institute (GRI) in Los Angeles, California. According to the late
James N. Wood, formerly president and CEO of the
J. Paul Getty Trust, "Thomas Gaehtgens is uniquely qualified to serve as director of the Getty Research Institute. His contributions to our appreciation and understanding of the visual arts through his own scholarship, his creation of opportunities for others, and his realization of a wide range of publications, combined with his international experience and network of colleagues, assure the continuing dynamism of the GRI and promises new opportunities for its exceptional staff." In 2009, Gaehtgens received the
Grand prix de la francophonie of the
Académie française and in 2011 an honorary doctorate from the
Paris-Sorbonne University. In 2011, he was elected a Fellow of the
American Academy of Arts and Sciences. In 2009, he published the first issue of the
Getty Research Journal, which features the work of established and emerging art historians, museum curators, and conservators around the world as part of the Getty's mission to promote critical thinking in the presentation, conservation, and interpretation of the world's artistic legacy. In 2011/2012, he co-curated
Pacific Standard Time: Art in L.A., 1945-1980, a scholarly collaboration of artists, curators, critics and over 60 cultural institutions across Southern California, coming together for six months to produce exhibitions that told the story of the birth of the Los Angeles art scene and how it became a major new force in the art world. According to
James Cuno, "Professor Gaehtgens is a committed internationalist, at home in German, French, and English, with students and scholar colleagues around the world sharing his internationalist values and joining him on research and professional projects that advance our common understanding of our world's shared artistic legacy." Gaehtgens retired from his position at the Getty in 2018. ==Private life==