In this study, a cost function is used to estimate the costs for California districts to meet the achievement goals set out for them by the state. I calculate estimates of base costs (i.e., per pupil costs in a district with relatively low levels of student need) and marginal costs (i.e., the additional costs associated with specific student characteristics) for poverty, English learners, and special education and then compare these estimates with the findings from cost studies in other states, which have used a variety of methods, and with other cost studies in California. Because of institutional constraints in California, the cost function estimate of total costs to achieve adequacy (which relies critically on the estimated relationship between spending and outcomes) may be quite imprecise. Nevertheless, the cost function estimates of base and marginal costs are not inconsistent with other studies, though they fall on the low end of the spectrum.