In 1914, Monnette was appointed to the Los Angeles Public Library Board, and reappointed every five years until his death in 1936. Monnette was elected President of the Library Board in 1916, and retained that office until his death as well. During the twenty-three years of his tenure, Monnette championed three major library bond packages which were supported by the citizens of Los Angeles. The bond packages allowed the city to build forty-eight (48) branches throughout the Los Angeles area as well as the landmark art deco Central Library in Downtown Los Angeles.