Health impact assessment (HIA) is a forward-looking, evidence-based tool used to inform stakeholders and policy makers about the potential health effects of proposed projects and policies and to identify options for maximizing potential health benefits and minimizing potential harm. This review examines how health equity, a core principle of health impact assessment (HIA), has been operationalized in HIAs conducted in the United States in one sector, transportation. Two perspectives on promoting health equity appear in the broader public health research literature; one aims at reducing disparities in health determinants and outcomes in affected populations, whereas the other focuses on facilitating community participation and self-determination. Variations in how these perspectives are applied in HIA informed our typology of five ways of addressing health equity in HIA. Transportation HIAs commonly included two of these—selecting vulnerable populations for the focus of the HIA and stakeholder engagement, seen in more than 70% of the 96 HIAs reviewed. Fewer than half of the HIAs assessed current health disparities or changes in their distribution. Only 15% of HIAs addressed equity by focusing on capabilities development or empowerment. Routinely assessing and reporting how an HIA aims to address health equity might better manage expectations and could make HIA practitioners and users more conscious of how an HIA can realistically be used to advance health equity.