Medicare beneficiaries with MCC are the heaviest users of health care services, however, there are few measures designed specifically to measure the quality of care provided to people with MCC. The MCC Measurement Framework identifies measurement concepts with the greatest potential for reducing factors of cost, reducing disease burden, and improving well-being. For a variety of reasons, it may be difficult for measure developers to gather MCC-related data systematically. Measures for the MCC population should assess care across episodes and across measured entities and staffing using a longitudinal approach. Delta measures over extended periods are particularly relevant. Formative testing may be particularly important early during development of MCC measures, not only for new tools designed for these measures, but also for testing the feasibility of linking data from a variety of sources.