In 1904 Ellen married Walter Pyle, Howard's younger brother, who owned a feather factory in Wilmington, She gave up her career as an illustrator in order to raise a family of four children. Two of her children became artists: her eldest daughter, Ellen, became a portrait painter after studying at the Pennsylvania Academy; her son, Walter, was an artist and illustrator and worked for the Federal Arts Project in Delaware during the late 1930s. Her youngest daughter, Caroline, married Nathaniel Wyeth, son of another Pyle student, N.C. Wyeth.
When her husband died in 1019, Ellen Pyle again turned to illustration in order to support her family. At her home "Westbrae" in Greenville, Delaware, she converted the hayloft of the barn into a studio. Her sister-in-law, Katharine Pyle, encouraged her to take her work to the Saturday EveningPost. The first covers the Post bought were a series of girls' heads with stylish bobbed hair. She sold the Post another painting of her daughter Caroline eating an ice cream cone, after making it more anecdotal by adding a dog intently watching. From 1926 until her death in 1036 her covers appeared regularly on the Post, along with those of Norman Rockwell and J.C. Leyendecker. In a letter of 1927 Rockwell praised her covers: "They [the coversj are dandy. So full of color and broadly painted, Believe me, I envy you the latter quality particularly."
She preferred the broad, loose quality of paint in the work of Dean Cornwell, rather than the tight, detailed style of Rockwell.
People identified with her subjects, which were drawn from everyday life such as the December 13, 1930, cover showing a grandmother with a young boy carrying a market basket and waiting for a bus on a cold, winter day. Other popular covers were a scene of a young woman in a blue roadster asking for road directions and one of children buying balloons.
Her models were usually her children or people she knew, placed in local surroundings, but they struck a responsive chord in the Post readers as being familiar, appealing, and typical of American life at the time. The type of American girl she portrayed was a wholesome, natural, unaffected girl who, to quote the artist, "likes to coast and skate in winter, who often goes without her hat, and who gets a thrill out of tramping over country roads in the fall." She also enjoyed painting young children and babies who were characterized by pudgy, red-cheeked faces and a healthy glow. Most of her work was for magazine covers and book jackets. She regretted not having time to devote to portraiture and landscape painting.