The Centers for Disease Control and Prevention and the Association of Public Health Laboratories co-sponsor the Laboratory Efficiencies Initiative (LEI), which is working to ensure a sustainable public health laboratory system. The group considers interstate test service sharing to be one of the most promising strategies for improving efficiency at public health laboratories. To assist laboratory directors and their colleagues who are considering sharing test services with each other, LEI recently published the Policy Guide for Public Health Laboratory Test Service Sharing. The guide is based on the actual experiences of 17 public health laboratory directors. It presents practical information to address common issues in sharing agreements, like liability concerns and exchange of funds.