Education plays an important role in determining individuals socioeconomic attainment and a nations competitiveness on the global stage. Thus, educational disparities not only prevent vulnerable populations from gaining access to a better life but also hinder a nations development. Theoretically, economic growth provides more resources for education. However, initial observations in many developing countries show that economic growth does not bring the same educational benefits to everyone. Vietnam offers an interesting context in which to study ethnic educational disparities in a developing country transforming from a centrally planned to a market-driven economy. After socioeconomic transformations, Vietnam has achieved significant progress, including economic and educational growth. However, educational disparities, especially in upper-secondary education, not only persist but have increased. Ethnic minority students continue to lag behind in upper-secondary school, despite the governments significant efforts to promote their education. Thus, understanding of ethnic educational disparities can yield recommendations for policymakers, parents, and educators regarding how to promote ethnic minorities educational success and assist in Vietnams broader socioeconomic development.To understand ethnic disparities in upper-secondary education in Vietnam over the last 20 years since the socioeconomic transformations, my dissertation comprises two studies. In Ethnic Disparities in Education after Vietnams Socioeconomic Transformations: Family Background and Residential Differences, I used data from the Vietnam Household Living Standard Surveys (9 waves of data collected between 1992 and 2014) to examine factors contributing to increases in ethnic educational disparities at the upper-secondary level. My findings confirmed that the ethnic disparities in three outcomes upper-secondary enrollment, attendance, and completion continue increasing. While residential differences slightly contributed to these disparities, family background differences, especially parental education and the rise in ethnic-based income inequality at the household level, explained these ethnic-based education disparities. In addition, I found that while household income contributions to the ethnic educational disparities tended to decrease, the role of parental education with respect to the ethnic-based educational disparities increased. These findings suggest important implications to policymakers, educators, and parents in promoting education among disadvantaged populations, especially ethnic minorities in Vietnam.Despite a number of challenges, some ethnic minority youths do enroll in and complete their upper-secondary education. Therefore, understanding how some ethnic minority students manage to overcome barriers and succeed educationally can also provide important insights regarding the means that policymakers, educators, and parents can pursue in order to address such educational disparities. With this aim, in my second study, Ethnic Minority Educational Success: Understanding Accomplishments in Challenging Settings, I used a mixed-methods approach and explored data from the Families and Communities in Transition (FACT) study to examine risk and protective or supportive factors pertaining to upper-secondary education among youth belonging to the Thai ethnic group, the second-largest ethnic minority group in Vietnam. The study found that early marriage, poverty, low-educated parents, low parental engagement in the child's education, school distance, being bullied or teased, and being encouraged by friends to drop out were challenges to ethnic minorities upper-secondary school enrollment and retention. More importantly, the study provided evidence that holding a positive attitude toward schooling oneself and enjoying effective support from parents, relatives, and peers (both in and out of school) can prevent ethnic minority students from dropping out of school and promote their educational success.