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Background: In this updated Self-Care of Coronary Heart Disease Inventory (SC-CHDI) v3.0, items were added to better reflect the theory of self-care of chronic illness and revised based on recent research. The expanded SC-CHDI now reflects the theoretical concepts of self-care maintenance, monitoring, and management. Objective: The aim of this study was to evaluate the psychometric properties of the SC-CHDI v3.0. Methods: In a sample of adults with coronary heart disease, we tested the SC-CHDI v3.0 validity with confirmatory factor analysis. Reliability was calculated using Cronbach α, factor score determinacy coefficient, and global reliability index for multidimensional scales, with values > 0.70 considered adequate. Results: The sample (n = 205) was predominantly male (79%) with a mean age of 65.3 ± 11.1 years. The self-care maintenance scale encompassed 2 distinct behaviors, namely, "illness related behaviors" and "health promoting behaviors," which reflect consulting and autonomous dimensions, respectively. The goodness-of-fit indices were adequate: χ 2 (25, N = 205) =31.86, P = .16, comparative fit index = 0.97, Tucker-Lewis Index = 0.95, root mean square error of approximation = 0.04 (90% confidence interval, 0.00-0.07), P = .705, and standardized root mean square residual = 0.045. Analysis of the new self-care monitoring scale yielded a single factor; goodness-of-fit indices were excellent: χ 2 (12, N = 205) =11.56, P = .48, comparative fit index = 1.00, Tucker-Lewis Index = 1.00, root mean square error of approximation < 0.001 (90% confidence interval, 0.000-0.07), P = .86, and standardized root mean square residual = 0.02. The self-care management scale had 2 dimensions of autonomous and consulting behavior with strong goodnessof-fit indices: χ 2 (7, N = 205) =6.57, P = .47, comparative fit index = 1.00, Tucker-Lewis Index = 1.00, root mean square error of approximation ≤ 0.001 (90% confidence interval, 0.00-0.08), P = .76, and standardized root mean square residual = 0.02. Reliability estimates were ≥0.80 for all scales. Conclusions: Our testing suggests that the SC-CHDI v3.0 is a sound measure of the essential elements of self-care for adults with coronary heart disease.