As growing numbers of Medicaid enrollees receive health benefits through comprehensive managed care (CMC), researchers and policymakers seeking to understand the service use of these enrollees must rely on encounter data that states receive from managed care plans. However, not all states report the encounter data submitted by their plans to the Medicaid Statistical Information System (MSIS), and, until recently, little was known about the data’s usability for research. This issue brief discusses the availability, completeness, and quality of encounter data for physician, clinic, and outpatient services (OT); inpatient hospital services (IP); and prescription drug services (RX) in the Medicaid Analytical eXtract (MAX) data, which are derived from MSIS. Knowing this information can help researchers and policymakers judge the usability of the 2010 and 2011 encounter data in MAX.