Clyde Chestnut Barrow was born into a poor farming family in Ellis County, Texas, near Telico, a town just southeast of Dallas. He was the fifth of seven children of Henry Basil Barrow (1874 – 1957) and Cumie Talitha Walker (1874 – 1942). The family migrated, piecemeal, to Dallas in the early 1920s as part of a wave of resettlement from the impoverished nearby farms to the urban slum known as West Dallas. The Barrows spent their first months in West Dallas living under their wagon. When father Henry had put together enough money to buy a tent, it was a significant improvement for the family.
Clyde was first arrested in late 1926, after running when police confronted him over a rental car he had failed to return on time. His second arrest, with brother Buck, came soon after, this time for possession of stolen goods (turkeys). Despite having legitimate jobs during the period 1927 through 1929, he also cracked safes, robbed stores, and stole cars. After sequential arrests in 1928 and 1929, he was sent to Eastham Prison Farm in April 1930. While in prison, Barrow used a lead pipe to crush the skull of another inmate who had sexually assaulted him repeatedly. This was Clyde Barrow's first killing, though another inmate already serving a life sentence took the blame. Barrow convinced another inmate to use an axe to chop off two of Barrow's toes to avoid hard labor in the fields; he would walk with a limp for the rest of his life as a result. Without his knowledge, Barrow's mother had successfully petitioned a release for him, six days after his intentional injury.
In 1930, Barrow escaped Eastham Prison Farm, using a weapon Parker had smuggled to him. Shortly after, he was recaptured and was sent back to prison. Later, paroled on February 2, 1932, Barrow emerged from Eastham a hardened and bitter criminal. His sister Marie said, "Something awful sure must have happened to him in prison because he wasn't the same person when he got out." A fellow inmate, Ralph Fults, said he watched Clyde "change from a schoolboy to a rattlesnake."
In his post-Eastham career, Barrow chose smaller jobs, robbing grocery stores and gas stations, at a rate far outpacing the ten or so bank robberies attributed to him and the Barrow Gang. His favored weapon was the M1918 Browning Automatic Rifle (called a BAR). According to John Neal Phillips, Barrow's goal in life was not to gain fame or fortune from robbing banks, but to seek revenge against the Texas prison system for the abuses he suffered while serving time.