OBJECTIVES: We investigated changes in hospital participation in local public health systems and the delivery of public health activities over time and assessed the relationship between hospital participation and the scope of activities available in local public health systems. METHODS: We used longitudinal observations from the National Longitudinal Survey of Public Health Systems to examine how hospital contributions to the delivery of core public health activities varied in 1998, 2006, and 2012. We then used multivariate regression to assess the relationship between the level of hospital contributions and the overall availability of public health activities in the system. RESULTS: Hospital participation in public health activities increased from 37% in 1998 to 41% in 2006 and down to 39% in 2012. Regression results indicated a positive association between hospital participation in public health activities and the total availability of public health services in the systems. CONCLUSIONS: Hospital collaboration does play an important role in the overall availability of public health services in local public health systems. Efforts to increase hospital participation in public health may have a positive impact on the scope of services provided and population health in US communities.