She led the committee to pass environmental legislation that protects open space, expands recycling programs, and promotes healthy city-infill strategies in the state.

Hancock also chaired the Assembly Select Committee on Bridging the Achievement Gap, which worked to reduce high dropout rates, improve school-to-career programs, and provide oversight of the federal No Child Left Behind Act.

In 2007, Governor Schwarzenegger signed legislation authored by Assemblywoman Hancock to greatly expand career technical education programs for high school students.

In 2005, Hancock authored AB 144, which provided financing for the construction of the new eastern span of the San Francisco-Oakland Bay Bridge.

She also served as a member of the Senate committees on Education, Governance and Finance, Environmental Quality, Human Services, and Agriculture.

In 2008, Hancock introduced SCA 5, which proposed to change the existing 2/3 supermajority requirement to pass a state budget with a simple majority vote rule.

Hancock drew national attention in 2011 for her introduction of SB 234, which proposed the imposition of a state sales tax on out-of-state internet companies, like Amazon.com, who sell goods in California.

Later that year, the Legislature and Governor Jerry Brown reached a compromise with several internet companies to incorporate many of the provisions of SB 234 in the state budget.

In 2013, Hancock authored and passed SB 260, which provides a parole hearing process for state prisoners who committed their crimes before age 18 and were prosecuted as an adult.

Later that year, Governor Brown signed SB 1279, which prohibits the use of state funds for the construction of new coal transportation projects.

In his bill signing message, the Governor remarked that "other localities should follow suit—and the state should, too—to reduce, and ultimately, eliminate the shipment of coal through all California ports."