By the mid-1940s, DeLay decided that she did not want to continue as a performer. In 1946, she returned to Juilliard to study with Ivan Galamian, becoming his assistant in 1948. In addition to teaching at Juilliard, she taught at Sarah Lawrence College, the University of Cincinnati – College-Conservatory of Music, the New England Conservatory, the Meadowmount School of Music and the Aspen Music Festival and School, among others. Her former students include many noted violinists of the late 20th century. She assisted Galamian with Itzhak Perlman. She also taught Anne Akiko Meyers, Albert Stern, Midori Goto, Akiko Suwanai, Sarah Chang, Philippe Quint, Kurt Sassmannshaus, , Cho-Liang Lin, Chin Kim, Ray Iwazumi, Shunsuke Sato, Nadja Salerno-Sonnenberg, Angèle Dubeau, Pierre Ménard, Dmitri Berlinsky, Nigel Kennedy, Alyssa Park, Yoon Kwon, Misha Keylin, Shlomo Mintz, Gil Shaham, Dezso and Tibor Vaghy, Fudeko Takahashi, William Fitzpatrick, Vilhelmas Čepinskis, Brian Lewis, and Li Chuan Yun, Brian Dembow, among others. She also taught many significant orchestral musicians and pedagogues, such as Simon Fischer, author of Basics; Paul Kantor, pedagogue at Rice University; Chicago Symphony Orchestra Concertmaster Robert Chen; Milwaukee Symphony Orchestra concertmaster Frank Almond; violinist and pedagogue Anton Miller; Philadelphia Orchestra Concertmaster David Kim; Liu Yang, and Lü Siqing, first Asian violinist to win 1st Prize at the Paganini Competition in Italy, among others. In a 1992 interview, Nadja Salerno-Sonnenberg said: "I think the greatest thing about Dorothy DeLay is that she has the ability to look at a young student or an old student and pretty much size up their character and the way that they think — their personality, basically — and how in a short period of time what's the best door to use to get them into here. And that's her method — the fact that there is really no method." Itzhak Perlman said of DeLay's pedagogic approach: "I would come and play for her, and if something was not quite right, it wasn't like she was going to kill me. She would ask questions about what you thought of particular phrases—where the top of the phrase was, and so on. We would have a very friendly, interesting discussion about 'Why do you think it should sound like this?' and 'What do you think of that?' I was not quite used to this way of approaching things." DeLay's students have gone forward to solo careers, principal orchestra positions with the world's leading orchestras, and have gone on to win many of the major violin competitions of the world. In 2003, Itzhak Perlman was appointed to his teacher's position at Juilliard, the Dorothy Richard Starling Chair of Violin Studies. The position was established in 1997 with a leadership grant from the Dorothy Richard Starling Foundation to The Campaign for Juilliard and was held by DeLay until the time of her death in March 2002.
