His father P. J. would have named him after himself, Patrick Joseph, but his mother reversed the names so Joseph wouldn't be immediately marked as Irish. Joe Kennedy came from a comfortable home; P. J. was in the liquor business, engaged in local politics and had investments in a local bank, the Columbia Trust. Joe made many friends at Boston Latin School and Harvard College but realized early on that his comfortable existence was a far cry from the Yankee Brahmin society that held most of the wealth in Boston.
Early in his career, Joe's job as state bank examiner made him privy to an attempt to take over the Columbia Trust, Boston's only Irish-owned bank. His reward for organizing a successful resistance to the takeover was the job of bank president at age 25. The next year, he inaugurated an even more esteemed Irish institution by marrying the eldest daughter of Boston mayor John Fitzgerald. Rose Fitzgerald Kennedy bore the first of their nine children the following summer.
Kennedy applied his considerable business acumen to a series of profitable forays into various industries. He played the stock market in the heady days before regulation and cashed out before the Crash of 1929. He went to Hollywood to produce movies, but quit after a notable disappointment. He ran the Somerset Company, importing liquor after -- and, it has been suspected, during -- Prohibition. He owned Chicago's Merchandise Mart, the largest office building in the world. Soon he was one of the richest men in America. The skills and contacts he acquired at each enterprise, by turns powerful, glamorous, and shady but always lucrative, proved invaluable for Joe's career and for his sons' futures.
Joe's involvement in politics began with his financial support of his father-in-law, Mayor Fitzgerald, during the reversed Congressional election of 1918. By 1932, he was backing a winner, Franklin D. Roosevelt. After refusing an ambassadorship to Ireland, Kennedy accepted the chair of the new Securities and Exchange Commission (SEC). Although commentators criticized the appointment, Kennedy served the SEC well for 14 months. After the next presidential election, Kennedy was made chair of the Maritime Commission, where he mediated between ship owners and unions -- according to him, "the toughest thing I ever did in my life." He finally received his plum assignment in 1937 as ambassador to Great Britain.
Ironically, soon after John F. Kennedy took the oath of office as president -- an ambition that Joe had harbored for himself -- Joe had a stroke, leaving him incapable of speech. For the last eight years of his life, he watched, mute, as John and Robert Kennedy weathered crises, triumphed, and then were each murdered. Joe Kennedy outlived four of his nine children. When he died in 1969, The New York Times estimated the value of his estate at half a billion dollars. President Kennedy said of his father: He "held up standards for us, and he was very tough when we failed to meet those standards. The toughness was important."
Most of this comes from the excellent PBS website.