Over the past 30 years, public health Practitioners worldwide have increasingly relied on Health Impact Assessments (HIAs) as a tool for informing decision makers of the potential health impacts of proposed policies, programs, and planning decisions. Adoption of the HIA is significantly less common in the United States than in international settings, with wider recognition occurring over the last decade. Many frameworks and procedures exist for conducting HIAs that could be adopted from international and domestic settings. In 2009, the United States adopted its first set of HIA practice standards through a consensus process that to date remains voluntary and unregulated. The absence of HIA national guidelines, amidst limited alternative methods for predicting the health effects of policy decisions, has resulted in wide variation in HIA practice across the United States. Such variations have resulted in decision makers questioning the consistency, accuracy, and validity of HIA findings and recommendations. Despite conformity challenges in United States HIA practice, little is known about Practitioners' views, on factors that promoted or hindered the influence on use of HIAs in non-health decision processes. The current general qualitative inquiry study presents United States HIA practitioner's experiences and perspectives regarding their roles as key health informants providing evidence-based information to non-health decision makers. The researcher used grounded theory (GT) methodology to understand the concepts most salient to key experts who conduct HIAs. The researcher used both purposive and snowball sampling techniques to recruit Practitioners with knowledge and experience in conducting HIAs in the United States, and conducted one-to-one semi-structured interviews with 12 HIA Practitioners representing public, private, and local health organizations to elicit personal views and lived experiences. These data were analyzed using thematic analysis to identify and categorize themes within the data, as well as to construct theories from the data showing commonalties, relationships, and overarching patterns between and within the thematic categories. The results indicated a need for understanding practitioner's perspectives in United States HIA practice. These results suggest that the views of HIA Practitioners are essential to improving acceptance, variability, and the future direction of HIA practice in the United States. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]