Economic development influences how a country functions, not simply in terms of financial concepts, but having a proper standard of living is also required, or in a sense, human development. The basic requirements necessary for individuals to achieve well-being are obtaining sufficient quantity and quality of education and healthcare. Using the Human Development Index (HDI) to measure human development is widely known to many economists and academics, yet the index has limitations as it mainly focuses on the quantitative aspect, which may cause the development concept to be overlooked. Therefore, this research, besides HDI, places strong emphasis on Human Capital Index (HCI), the measures of both quantity and quality of health and education, hoping to draw more attention to this index along the way and emphasizing the importance of the study that lies in highlighting the quality factors of human development. This paper will examine how human capital and external elements influence human development, and how human development, in turn, influences economic growth, in which the literature review provides insights into the topic in general, whereas data analysis will concentrate on the case of Cambodia. The finding suggests that human capital contributes to human development and economic growth; however, challenges in governance, social protection, and sustainability oversight have delayed the progress of human development in Cambodia, which suggests that Cambodia should work on these challenges as well, in addition to investing in human capital to achieve development.