The California Budget Act of 2012, through a trailer bill known as Senate Bill (SB) 1041, contained significant reforms to the California Work Opportunity and Responsibility to Kids (CalWORKs) program. CalWORKs is California's Temporary Assistance for Needy Families (TANF) program, a central component of the safety net that provides cash aid for low-income families with children. The SB 1041 reforms to CalWORKs aim to engage participants in more-intensive work activities as early as possible, while also providing more flexibility in work activity options and increased incentives for work as participants move toward self-sufficiency. The California legislature included a provision in the bill for an independent evaluation to determine if SB 1041 achieves its objectives and if there are any unintended consequences. Evaluation of the SB 1041 Reforms to California's CalWORKs Program: Background and Study provides background on the SB 1041 policy changes and an overview of the evaluation plan. The authors highlight the factors that motivated the changes to CalWORKs, summarize the key reforms, delineate the questions underlying the SB 1041 evaluation and the evaluation approach, and explain the evaluation timetable, products, and expected utility. To determine if SB 1041 is achieving its objectives and if there are any unintended consequences, a series of reports will document the way the SB 1041 reforms were implemented across California's 58 counties, how the changes affected the number and composition of CalWORKs participants and their experience with program services, and the impact of the reforms on families and children, as well as the operations of county welfare offices. The multiyear, multicomponent evaluation will draw on primary and secondary data and employ qualitative and quantitative methods. The project was launched in July 2014 and will be completed in December 2017. Results will be made available through a series of reports released at the end of calendar years 2015, 2016, and 2017. Three appendices are included: (1) State Welfare Policies; (2) Sources of Data for Evaluation; and (3) Analytic Approach.