Coatsworth, born in Buffalo, NY, and a graduate of Vassar (1915) and Columbia (1916), was the wife of Henry Beston (q.v.; married 1929) and lived with him in Hingham, Mass. and then on a farm in Nobleboro for decades. Coatsworth travelled widely, spending time in England, France, Spain, Italy, Greece, Egypt, Morocco, Japan, China, Mexico, the Philippines, and the Yucatan. She incorporates her travel memories into her writing.
Coatsworth wrote over 90 books, most of them children's books, including The Cat and the Captain (1927), Toutou in Bondage (1929; the adventures of a fox terrier in Morocco), The Boy With the Parrot (1929; a story of Guatemala), Away Goes Sally (1934; travels from Mass. to Maine by ox team), Sword of the Wilderness (1936; Maine boy captured by Indians), Alice All By Herself (1937; 10-year-old girl in Damariscotta), Five Bushel Farm (1939; companion to Away Goes Sally), Houseboat Summer (1942; two children explore Damariscotta), Thief Island (1943; father and two kids on deserted Maine island), The Little Haymakers (1949; boy and pair of oxen), The Captain's Daughter (1950; setting is old Thomaston), Dollar for Luck (1951; on trading ship off Maine coast, late 19th century), Door to the North, A Saga of 14th Century America (1952), Cat Stories (1953), Mountain Bride (1954; modern version of old Abenaki Indian legend), The Last Fort, A Story of the French Voyageurs (1958), The Peaceable Kingdom and Other Poems (1958), The Nobel Doll (1961), and Bob Bodden and the Goodship Rover (1968). Coatsworth won the 1931 Newbury Award for her children's book, The Cat Who Went To Heaven (1930; set in Japan).
Her first novel, Here I Stay: A Maine Novel, was written in 1938. Her Maine Memories: Vignettes of Life around Damariscotta (1944) was the first of several autobiographical books, including Personal Geography: Almost an Autobiography (1976). Maine Ways (1945) contains stories and anecdotes of the Maine way of life.
Books of poems include her first book, Fox Footprints (1923), Atlas and Beyond (1924), Compass Rose (1929), Country Poems (1942), and Summer Green (1948).