Robert Lawson was born in 1892. Others in his immediate generation were Percy Crosby and Dorothy Lathrop. He grew up in Montclair, New Jersey and went to the New York School of Fine and Applied Arts after graduation.
His earliest work is reported to be in 1914 when he had his first studio in Greenwich Village and "did magazine illustration, stage settings, and some commercial work."
He quickly settled on pen & ink as his medium of choice and by 1921 he was producing complex images for Century. In 1922 he produced illustrations for his first book, The Wonderful Adventures of Little Prince Toofat.
Lawson began writing many of his own stories in 1939 and started with the famous Ben and Me - a story of a mouse and his Ben Franklin. His Rabbit Hill won the Newbery Medal in 1944 (as did the book Adam of the Road which he illustrated for Elizabeth Janet Gray). His biography of his ancestors, They Were Strong and Good, won the Caldecott Medal for 1940.
Other famous books that he illustrated were Sword in the Stone by T.H. White (1939), Poo Poo and the Dragons by C.S. Forester (1942), and his own Capt. Kid's Cat and Mr. Revere and I. Many of his books are still in print.
(source: http://www.bpib.com/illustrat/lawson.htm)