Douglas Duer was born in October 1887 in Pikesville, Maryland, to Margaret and Andrew Duer.  His father died in 1891 leaving nine children of which Douglas, aged four, was the youngest.  He was educated at Marston’s School in Baltimore.  Young Duer’s talent for art was noticed by his sister, Henrietta, whi was a portrait painter, and she encouraged her brother’s interests.  After four years of working in the family business, Duer studied for one year at the Philadelphia Academy of The Fine Arts under William Merit Chase. Then, in 1909 he came to study with Howard Pyle in Wilmington, where he shared a studio at 1305 Franklin Street with Leslie Thrasher and Eads Collins. During this time he established himself as an illustrator of both magazines and books, including Riders of the Purple Sage by Zane Grey in 1912, and poems by William Rose Benet.

In 1917, Duer enlisted in the army and served in France with the fortieth engineers, working with camoflage.  After the end of the war, he went on detached service in France and Germany, where he traveled in advance of occupying troops to copy German camoflage before it’s destruction.  Duer stayed in touch with several Pyle students during the war, especially  Leslie Thrasher.

Duer returned to the United States in 1919, weakened by a severe illness. Yet, he resumed his art work and began the ten most productive years of his illustrating career. At the end of 1922 or the beginning of 1923, he moved to New York and set up a studio at 51 West Tenth Street. From 1919 to 1929 he illustrated for American Magazine, Country Gentleman, Everybody’s,  Pictorial Review, and many others. In 1928, Doer moved to Philadelphia.  As well as working as an illustrator, he commuted weekly to Wilmington to teach at the Wilmington Academy of Art.
With he Depression came a change in the market for illustration, Duer, like many other illustrators, was affected by the difficult times. He found work in public programs, specifically in the mural programs in Philadelphia and, later, the WPA.  One of his morals was executed for the Philadelphia School Board at the J.S. Jenks School in Chestnut Hill, Philadelphia The artist also made dioramas at this time.

In the late 1930’s Duer returned to a small amount of bookjacket illustration, and in the 1940s he undertook advertising work. For a time, he was the art director for Beacom Chemical Company in Philadelphia and also designed greeting cards. Doer suffered a severe heart attack in 1952 and retired from all ciommercial work to paint solely for his own pleasure. Until his death in 1964, he painted mainly landscapes and figures, as well as enjoyed experimentation with different media and techniques. He also returned to writing, which had been an interest since his youth.