Green was actively engaged with the early years of Lafayette College, serving at various times as a professor, trustee, and acting president.

[3] Immediately following his graduation, Green was appointed to the Philadelphia dispensary, where he worked for one year before opening up his own medical practice in Easton.

[4] Knowledgeable in the field of medicine, Green was asked in 1837 by the newly-formed Lafayette College if he would become the school's professor of chemistry, a role in which he taught for another four years.

While at the school, Green worked alongside James Henry Coffin, an individual also interested in the sciences, and more specifically, meteorology.

[6][7] Upon the donation of this astronomy building, Green asked then-president William Cassady Cattell that his name not be mentioned upon the laying of the cornerstone.