Nishio, MasakoThe purpose of this study is to examine a rapidly growing educational phenomenon in the United States: private supplementary instruction (private tutoring). This instruction is offered out-of-school time, focused on academic subjects, and provided mostly for a fee. Its primary goal is to help students prepare for college entrance examinations (advancement), or address difficulties in academic subjects (remedial). Using the concept of human capital as the primary theoretical framework, the study examines possible reasons for the use of private supplementary instruction and possible benefits that accrue to individuals from its use. The study examines if families with higher levels of educational aspirations or less academic satisfaction with their schools are more likely to use private supplementary instruction. It also considers whether students who use supplementary instruction have higher gains in mathematics achievement or higher likelihood of college acceptance. Data for this study come from the National Education Longitudinal Study and includes approximately 7,600 students who attended high school between 1990 and 1992. Students and parents were asked about the use of private supplementary instruction when students were 12th graders. Follow-up surveys in 1994 indicated students' post-secondary enrollment status two years later. Analyses of the use and effects of private supplementary instruction are calculated using OLS and logistic regressions. The research findings indicate that families with higher levels of educational aspirations are more likely to use advancement supplementary instruction, and doing so improves students' chance of college acceptance. Advancement instruction may also improve the academic performance of students, particularly students from high-income families. Use of remedial instruction, however, does not seem to improve academic performance or the likelihood of college acceptance for most students, though Asian Americans and African Americans may be exceptions. Family income also appears to play a role in both the use and effects of private supplementary instruction. Although human capital theory helps to explain specific aspects of private supplementary instruction, especially aspects associated with the use of advancement instruction, the study also demonstrates that issues related to use and effects of private supplementary instruction require additional theories to account for social and cultural factors.en-USDissertationEducation, SecondaryEducation, BusinessEducation, Generaltutoringcoachingsecondary educationNo Child Left Behind (NCLB)private sectorhuman capital