The intent of the guide is to support current and prospective practititioners of impact assessment in California and the United States, to foster thoughtful and high-quality use of HIA, and to promote consideration of health in all policies. The Guide provides a brief background on HIA, an outline of essential and common tasks in the HIA process, discussion of common issues and challenges encountered in the HIA process, examples of and links to resources for practice. It also provides suggestions for integrating health analysis within the regulatory environmental impact assessment process, obtaining inclusion from diverse stakeholders, and evaluating the HIA process. The Guide may be useful for public health or regulatory agencies responsible for implementing HIAs. This Guide is not proscriptive, definitive, or exhaustive, nor is it a methodological toolkit for all HIA analysis. The guide does not address how to develop the capacity to conduct or institutionalize HIA (e.g., technical skills), how to construct a project team, budgeting, etc. The resources section of the guide provides links to other articles, guidance documents, and references that provide complementary information.