The National Guard Youth ChalleNGe program is a residential, quasi-military program for youth ages 16 to 18 who are experiencing difficulty in traditional high school. This report covers the program years 2018-2019 and is the fourth in a series of annual reports that RAND Corporation researchers have issued over the course of a research project spanning September 2016 to June 2020. Each annual report documents the progress of participants who entered ChalleNGe during specific program years and then completed the program. A focus of the ongoing analysis of the ChalleNGe program is collecting data in a consistent manner. Based on these data, each report also includes a trend analysis. In this report, researchers provide information in support of the National Guard Youth ChalleNGe Program's required annual report to Congress. In addition to information on participants who entered the ChalleNGe program and completed it in 2018, the authors include follow-up information on those who entered the program and completed it in 2017. Finally, they describe and provide syntheses of other ongoing research efforts to support the ChalleNGe program. Methods used in this study include site visits, collection and analyses of quantitative and qualitative data, literature reviews, and development of tools to assist in improving all program metrics -- for example, a program logic model. Caveats to be considered include some documented inconsistencies in reported data across sites, a focus on those who completed the program and not on all participants, and the short-run nature of many of the metrics reported.