The goal of patient-centered communication (PCC) is to help practitioners provide care that is concordant with the patient's values, needs and preferences, and that allows patients to provide input and participate actively in decisions regarding their health and health care. PCC is widely endorsed as a central component of high-quality health care, but it is unclear what it is and how to measure it. PCC includes four communication domains: the patient's perspective, the psychosocial context, shared understanding, and sharing power and responsibility. Problems in measuring PCC include lack of theoretical and conceptual clarity, unexamined assumptions, lack of adequate control for patient characteristics and social contexts, modest correlations between survey and observational measures, and overlap of PCC with other constructs. We outline problems in operationalizing PCC, choosing tools for assessing PCC, choosing data sources, identifying mediators of PCC, and clarifying outcomes of PCC. We propose nine areas for improvement: (1) developing theory-based operational definitions of PCC; (2) clarifying what is being measured; (3) accounting for the communication behaviors of each individual in the encounter as well as interactions among them; (4) accounting for context; (5) validating of instruments; (6) interpreting patient ratings of their physicians; (7) doing longitudinal studies; (8) examining pathways and mediators of links between PCC and outcomes; and (9) dealing with the complexity of the construct of PCC. We discuss the use of observational and survey measures, multi-method and mixed-method research, and standardized patients. The increasing influence of the PCC literature to guide medical education, licensure of clinicians, and assessments of quality provides a strong rationale for further clarification of these measurement issues.