The results of testing two instruments for consequential decision making are reported: a screening instrument, the Decision Making Quality Scale (DMQS), which assesses the degree to which a person adheres to seven quality criteria of decision making; and a diagnostic measure, the Decision Making Quality Inventory (DMQI), which assesses an individual's dominant decision-making style through six sequential stages of the process. The instruments are conceptually linked through the same theoretical framework, the Janis and Mann (1977) conflict model of decision making, as well as operationally linked as counterpart instruments. Feasibility of the instruments was demonstrated with low readability indexes, reasonable administration times, and respondent acceptability by six samples (N = 766). Content validity was supported by panels of experts in decision theory. Reliability coefficients were consistently high (>.70) for all samples. Support for construct validity was obtained using the contrasted groups approach and relationship testing. The instruments are ready for research and clinical use with healthy adolescents and their parents, as well as with adolescents and young adults who have experienced a chronic illness such as cancer and with their parents.