In 2015 Medicare launched the Physician Value-Based Payment Modifier program, the largest US ambulatory care pay-for-performance program to date and a precursor to the forthcoming Merit-based Incentive Payment System. In its first year, the program included practices with a hundred or more clinicians. We found that 1,010 practices met this criterion, 899 of which had at least one attributed beneficiary. Of these latter practices, 263 (29.3 percent) failed to report performance data and received a 1 percent reporting-based penalty. Of the 636 practices that reported performance data, those that elected quality tiering—voluntarily receiving performance-based penalties or bonuses—and those with high use of electronic health records had better performance on quality and costs than other practices. Practices with a primary care focus had better quality than other practices but similar costs. These findings translated into differences in the receipt of penalties and bonuses and may have implications for performance patterns under the Merit-based Incentive Payment System.