Objective Examine the extent to which physician organization participation in an accountable care organization (ACO) and electronic health record (EHR) functionality are associated with greater adoption of care transition management (CTM) processes. Data Sources/Study Setting A total of 1,398 physician organizations from the third National Study of Physician Organization survey (NSPO3), a nationally representative sample of medical practices in the United States (January 2012—May 2013). Study Design We used data from the third National Study of Physician Organization survey (NSPO3) to assess medical practice characteristics, including CTM processes, ACO participation, EHR functionality, practice type, organization size, ownership, public reporting, and pay‐for‐performance participation. Data Collection/Extraction Methods Multivariate linear regression models estimated the extent to which ACO participation and EHR functionality were associated with greater CTM capabilities, controlling for practice size, ownership, public reporting, and pay‐for‐performance participation. Principal Findings Approximately half (52.4 percent) of medical practices had a formal program for managing care transitions in place. In adjusted analyses, ACO participation (p < .001) and EHR functionality (p < .001) were independently associated with greater use of CTM processes among medical practices. Conclusions The growth of ACOs and similar provider risk‐bearing arrangements across the country may improve the management of care transitions by physician organizations.