Each year, state Medicaid programs are required to make choices about how best to apportion limited Medicaid dollars for long term services and supports (LTSS). The statutory framework under which Medicaid LTSS operates allows states to develop and implement LTSS programs tailored to the specific needs and circumstances of their beneficiaries. The resulting variability in programs presents an opportunity to identify program designs and policies that offer the best value – high-quality, accessible LTSS services that are financially sustainable. But, in concert with evidence on benefits of LTSS, key to determining value is accurate longitudinal data on how much states are spending on LTSS and what that spending buys. This paper examines the three primary sources of data on state Medicaid LTSS expenditures and beneficiaries: periodic reports submitted by states to the federal government, data from the Medicaid Statistical Information System (both the legacy system and the current, transformed system), and state surveys. We summarize the purpose and content of each data source, describe their strengths and limitations, and highlight the reliable data points from each that may be used by policymakers and researchers. We also describe significant trends in LTSS spending and beneficiaries that can be gleaned from the existing data.