Electronic health records are expected to improve all six dimensions of quality care identified by the Institute of Medicine (safety, timeliness, effectiveness, efficiency, equity, and patient-centeredness). HealthTexas Provider Network, the ambulatory care network affiliated with the Baylor Health Care System in Dallas-Fort Worth, Texas, is implementing a networkwide ambulatory electronic health record (AEHR). To evaluate the quality of care and financial impact of the AEHR implementation, we examined the available indicators for quantitatively measuring performance in each dimension of quality. For patient-centeredness, the primary data source available is the patient satisfaction survey. To achieve a broad view of patient-centeredness, we identified two measures of satisfaction (overall satisfaction with the physician and willingness to refer the physician) to be examined individually and used additional survey items to construct physician interaction and organizational scales. These scales showed good reliability (Cronbach alpha = 0.95 and 0.89, respectively) and predictive ability ranging from 77% to 93% when applied to the overall satisfaction measures. Data from September 2003 to June 2006 showed mean pre-AEHR implementation baseline performance of 22.9 (±3.3) on the 25-point physician interaction scale and 38.0 (±5.8) on the 45-point organizational scale; 70.9% of patients reported excellent satisfaction with their physician, and 97.6% of patients reported willingness to refer. Timeliness data were collected using the same survey. Baseline performance showed that 43.4% of patients waited <2 days between making and keeping an appointment, and 50.6% of patients waited <5 minutes past appointment time. However, 12.5% waited >30 days between making and keeping an appointment, and 14.0% waited >30 minutes past appointment time. The power to detect changes in the patient-centeredness and timeliness measures in the 3-year multiple time series evaluation of the quality and financial impact of the AEHR was investigated and showed that even small changes in these measures will be detectable.