Strong primary care systems are often viewed as the bedrock of health care systems that provide high-quality care, but the evidence supporting this view is somewhat limited. We analyzed comparative primary care data collected in 2009-10 as part of a European Union-funded project, the Primary Health Care Activity Monitor for Europe. Our analysis showed that strong primary care was associated with better population health; lower rates of unnecessary hospitalizations; and relatively lower socioeconomic inequality, as measured by an indicator linking education levels to self-rated health. Overall health expenditures were higher in countries with stronger primary care structures, perhaps because maintaining strong primary care structures is costly and promotes developments such as decentralization of services delivery. Comprehensive primary care was also associated with slower growth in health care spending. More research is needed to explore these associations further, even as the evidence grows that strong primary care in Europe is conducive to reaching important health system goals.