California policymakers have established the expectation that all public school students should have access to a broad course of study, in classes where instruction is consistent with the state's content standards. Further, the state holds schools and school districts accountable for their ability to ensure that all students achieve at a specified level of academic proficiency, attend school regularly, and graduate from high school prepared for adult success. This brief puts California's K-12 funding system into context by comparing the state's school finance system to other states, both in terms of funding levels and policy. It also summarizes the results of an adequacy study that takes on the difficult task of estimating how much funding might be enough, using a professional judgment approach to provide some insights into the resources likely needed for adequate schooling. [This brief summarizes three "Getting Down to Facts II" technical reports on funding levels in California: "Adequacy and State Funding Formulas: What Can California Learn From the Research and National Context?" (ED594606), "District Dollars 2: California School District Finances, 2004-05 through 2016-17" (ED594665), and "What Does It Cost to Educate California's Students? A Professional Judgment Approach" (ED594739).]