From 1997 to 2004, Leal served as Treasurer of San Francisco, the City and County's banker and chief investment officer, winning re-election in 2001. Her duties as Treasurer also included managing all tax and revenue collection for San Francisco as well as managing billions of dollars in short-term revenue. She introduced the first socially responsible investment portfolio among California’s 58 counties. Her socially-responsible portfolio’s return on investments surpassed the other 57 other California counties during her tenure. She helped increase tax collection rates, including a 91% increase in delinquent revenue collection, representing tens of millions in additional revenue. Leal spearheaded the city's e-commerce initiative, which was named one of the top e-government projects nationwide and helped launched the nation's first audio ATM for the visually impaired.