“The best estimate of treatment effect to be expected from a patient treated outside the trial is still the overall estimate.” —Robert Califf and David DeMets1 A number of ambulatory heart failure therapies have been shown to be efficacious when studied in randomized controlled trials. These include angiotensin-converting enzyme inhibitors (ACEI), angiotensin receptor blockers (ARB), β-blockers (BB), aldosterone antagonists (AA), implantable cardioverter defibrillators (ICD), cardiac resynchronization therapy (CRT), anticoagulation, and education. On the basis of these data, clinical practice guidelines recommend these therapies in appropriately selected patients.1a,–,3 For those well supported recommendations for which there is also sufficient simplicity in use and transparency of contraindications, process performance metrics have been adopted as measures of quality. Article see p 1601 However, treatment effects seen in trials are derived from patient populations that are generally much younger, with less comorbidity than is encountered in routine clinical care.4,5 Trials are also conducted under idealized circumstances under closer monitoring than often occurs after widespread uptake of therapies as standard of care. This potential difference between idealized efficacy and real-world effectiveness has encouraged an increasing number of observational studies of evidence-based therapies in the general patient population. In this issue of Circulation , Fonarow and colleagues6 report the association between performance on 7 current and emerging outpatient heart failure process-of-care measures (ACE/ARB, BB, AA, CRT, and ICD for patients with reduced left ventricular ejection fraction, anticoagulation for patients with atrial fibrillation, and heart failure education) and subsequent clinical outcomes. This analysis is made possible by the Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE HF), which provides one of the few comprehensive looks at outpatient heart failure care in the United States. For this reason, IMPROVE HF is …