His ability to connect with corporate leaders led to a career in management consulting. Mr. Bain founded his own consulting company, Bain & Co., in 1973. In 1984, he founded Bain Capital, a private-equity investment firm, where he installed Mitt Romney as its top executive. Mr. Bain died Tuesday at his home in Naples, Fla. He was 80 and had been suffering from Alzheimer’s disease. William Worthington Bain Jr. was born July 30, 1937, in Johnson City, Tenn. His father, who had little formal education, was in the wholesale grocery business. William Jr. enrolled initially at East Tennessee State University in his hometown and then, after two years, transferred to Vanderbilt. His father cashed in life insurance policies to help pay the tuition. The younger Mr. Bain graduated from Vanderbilt with a history degree in 1959 with Phi Beta Kappa honors. Black & Decker was an early client for his new firm, and Mr. Bain became a lifelong friend with the tool maker’s chairman, Francis Lucier. Mr. Bain decided he should seek other ways to benefit from the firm’s ability to provide performance-enhancing advice. That led to the formation of Bain Capital, which acquired stakes in companies, revved up their financial results and then sold them. The job cuts that often result from such private-equity deals proved a political problem for Mr. Romney when he ran unsuccessfully for president as the Republican candidate in 2012. His critics accused him of destroying jobs, a charge he denied. In 1990, during an economic slump, Bain announced a layoff of about 17% of its workers, and Mr. Bain and seven other original owners agreed to sell their remaining 70% stake in the firm to colleagues for an undisclosed sum. After retiring from Bain & Co. and Bain Capital, Mr. Bain helped found a smaller private-equity firm, Bain Willard. He became an owner and director of Hinckley Yachts, a maker of luxury boats. Mr. Bain is survived by his wife of 20 years, Ann Dean Bain. Two earlier marriages ended in divorce. Survivors also include a brother, four children and three grandchildren.