Physician groups are increasingly being vertically integrated with hospitals and health systems; yet, the evidence on the impact of physician-system integration on health system outcomes is mixed. The objective of this study was to examine the impact of increased physician-system integration on select health system outcomes. We used a mixed-methods approach: (1) a fixed-effects multivariate mediation analysis; and (2) a qualitative analysis of interviews with health executives (n = 25). Our findings showed that hospitals spent $633 375.22 to $827 110.24 for each "level" increase in integration. This relationship was attenuated, however, by the presence of care coordination mechanisms.