Objective: To evaluate the quality of evidence produced by studies of the chronic care model (CCM). Study Design: Systematic review using a grading system in which grades are assigned on the basis of the hierarchy of evidence, study limitations, and analytical attempts to mitigate limitations. Data Collection: Systematic literature search yielding 159 published studies, of which 28 met inclusion criteria. Principal Findings: Of the 28 studies, 14.3% were graded as “A” or “A-,” 14.3% as “B,” 7.1% as “C-,” and 64.3% as “D.” Overall, 46.4% of the studies committed one or more serious errors, nearly 40% committed one or more design-specific flaws, and over 70% committed one or more minor flaws. Conclusions: Methodological quality undergirds all evidence-based medicine because without strong evidence supporting or refuting the efficacy of an intervention, the movement toward basing medical decisions and practice on scientific evidence is not sustainable.