This dissertation is comprised of three autonomous chapters on topics in labor economics. The first chapter exploits the quasi-random assignment of students into classrooms in a large secondary school in Malaysia to estimate the effects of peers on student outcomes. The estimates show that having better achieving classmates improves a student's math achievement and reduces the student's incidence of class absences and discipline violations. There is also evidence of non-linear peer effects and that average achievement may increase as a result of ability grouping. The second chapter extends Iannaccone's (1992) religious club model to explain why the Amish would collectively object to high school education and refuse to comply with compulsory schooling laws. I utilize the surprising 1972 U.S. Supreme Court's decision in Wisconsin vs. Yoder, which exempts Amish children from compulsory high school education, as a policy shock to test the predictions of the model. The results show that the successful restriction on high school education helped the Amish sect exclude individuals who have high labor productivity and would lower the quality of the sect from joining. The evidence supports the idea that the Amish use the restriction on secular education as a religious sacrifice to screen out uncommitted members. The third chapter investigates the effect of higher immigration on native fertility. Previous research shows that immigration affects wages, income, and the cost of child rearing, while standard fertility model predicts that changes in wages, income, and the cost of child rearing would affect fertility. Using the cross- state variation in the total fertility rates of native- born American women and the share of immigrants in the population between 1970 and 2005, this chapter estimates that for every one percentage point increase in the share of immigrants in the population, native total fertility rate is predicted to increase by roughly 0.01 children. The negative effect of immigration on wages is the most likely explanation, because the fertility of less educated women and women who resided in their states of birth is most affected