[17] With his savings and a small inheritance from his grandfather, Coolidge opened his own law office in Northampton in 1898. He practiced commercial law, believing that he served his clients best by staying out of court. As his reputation as a hard-working and diligent attorney grew, local banks and other businesses began to retain his services.[18]

Marriage and family
Grace Coolidge
In 1903, Coolidge met Grace Goodhue, a University of Vermont graduate and teacher at Northampton's Clarke School for the Deaf. They married on October 4, 1905, at 2:30 p.m. in a small ceremony which took place in the parlor of Grace's family's house, having overcome her mother's objections to the marriage.[19] The newlyweds went on a honeymoon trip to Montreal, originally planned for two weeks but cut short by a week at Coolidge's request. After 25 years he wrote of Grace, "for almost a quarter of a century she has borne with my infirmities and I have rejoiced in her graces".[20]
The Coolidges had two sons: John (1906–2000) and Calvin Jr. (1908–1924). 