In 1873, Lathrop again returned to New York to help his family financially. He taught painting at Cooper Institute in Manhattan and became known for his illustrations, painted portraits, and designed stained glass.At this point in his career, Lathrop concentrated on producing decorative work. He designed the chancel of Trinity Church in Boston, Massachusetts, decorated the interior of the Bowdoin College Chapel in Brunswick, Maine, and decorated several churches in New York. The Marquand Memorial Window, installed in the original Marquand chapel at Princeton University, was an example of Lathrop's work in stained glass. The chapel and the Lathrop window were destroyed by fire in 1922. Lathrop's last work was a series of medallions for the building of the Hispanic-American Society in Manhattan.
