The first essay of this dissertation examines the role of teacher characteristics in schools on student outcomes using datasets from TIMSS 1999 and TIMSS 2007 international tests. Taking an advantage that students have to take both mathematics and science subjects from different teachers, I use the method of First Difference (FD) analysis in order to remove the potential biases between teacher attributes and unobserved student characteristics. The findings show some contradictory outcomes between the FD analysis and ordinary least squares (OLS) analysis. The second essay looks into the problem of recruitment of well-qualified high school and college graduates to work as primary and secondary school teachers. I compare teacher salaries and benefits vis-à-vis other mathematics and science-oriented professions namely medical professions, engineers, accountants, scientists and nurses. In addition, I compare incomes between people who graduate from teacher colleges and non-teacher colleges. Using data from Thailand Labor Force Survey from 1985 to 2005, I find that teachers are the most poorly paid of all professions, including nurses. The difference in terms of an opportunity cost between male and female teachers is also striking. Among the graduates from teacher colleges, male graduates earn more than their peers if they chose other occupations whereas female graduates earn less if they make other choices. The third essay looks at the reasons teachers choose part-time jobs, the type of jobs they choose, and the amount of income they receive from these jobs, as well as factors influencing these decisions. I find that approximately 20-25% of Thai teachers participated in moonlighting activities. The majority of them have part-time jobs including tutoring, selling food and other products, and farming. Low salaries and high level of indebtedness are the most important factors associated with the increased likelihood of having a part-time job. However, economic status does not correlate significantly with their decision to tutor as their part-time job.