After returning to England in 1896 to marry, she resumed research she had initiated at Gӧttingen into an equation to determine the orbit of a comet. Her husband continued his work coaching in mathematics. However, in 1897 they both returned to Gӧttingen, encouraged by Felix Klein. Both attended advanced lectures and while she continued her mathematical research her husband started to work creatively for the first time. They visited Turin in Italy to study modern geometry and under Klein's guidance they began to work in the new area of set theory. From about 1901, the Youngs began to publish papers together. These concerned the theory of functions of a real variable and were heavily influenced by new ideas with which she had come into contact with in Gӧttingen. In 1908 they moved to Geneva in Switzerland where she continued to be based while her husband held a series of academic posts in India and the UK.