The author conducted a structured literature review of instruments for evaluating shared medical decision making. She included relevant instruments that were generalizable beyond specific situations and had been formally evaluated and organized them by domains of values or preferences, information and communication in decision making, and other aspects of decision making. For values or preferences, the author identified 11 instruments, mostly on preferences for roles and information. For information and communication, she found a systematic review of instruments for observational assessment of decision making, 3 additional observational instruments, and 3 questionnaires. For other aspects of decision making, the author identified 3 instruments in domains such as decision self-efficacy and 4 multidimensional instruments. Although instrument development tended to cluster in several areas and there were clear gaps in the literature, the diversity of instruments demonstrates the broad range of constructs involved in assessing shared decision making.