Objective To provide metrics for quantifying the capability of hospitals and the degree of care regionalization. Data Source Administrative database covering more than 10 million hospital encounters during a 3‐year period (2012–2014) in Massachusetts. Principal Findings We calculated the condition‐specific probabilities of transfer for all acute care hospitals in Massachusetts and devised two new metrics, the Hospital Capability Index (HCI) and the Regionalization Index (RI), for analyzing hospital systems. The HCI had face validity, accurately differentiating academic, teaching, and community hospitals of varying size. Individual hospital capabilities were clearly revealed in “fingerprints” of their condition‐specific transfer behavior. The RI also performed well, with those of specific conditions successfully quantifying the concentration of care arising from regulatory and public health activity. The median RI of all conditions within the Massachusetts health care system was 0.21 (IQR, 0.13–0.36), with a long tail of conditions that were very highly regionalized. Application of the HCI and RI metrics together across the entire state identified the degree of interdependence among its hospitals. Conclusions Condition‐specific transfer activity, as captured in the HCI and RI, provides quantitative measures of hospital capability and regionalization of care.