In this dissertation, I empirically investigate the changes in the market structure after new entrants, and how these changes affect the welfare of market participants. In Chapter 1, using records for public and charter schools in New York City, I empirically show that public schools adjusted after charter schools entered the neighborhood. I construct a school-specific curriculum index from textual data to look into changes not only in vertical school quality but also in horizontal curriculum differentiation. One difficulty in studying charter school spillover effects is the concern on endogenous charter school locations. The research design leverages the co-location policy in NYC to overcome this concern. The co-location policy allows charter schools to share the building with public schools and therefore facilitates the entry of charter schools, which exogenously shifts the probability of charter school entry in different neighborhoods since such excess capacity is not evenly distributed across the city. Instrumental variable regression shows that the public schools under charter school competition are more likely to increase their teaching quality, and also adjust their after-school activities to be more attractive to White and Asian families. In Chapter 2, I use a structural model to separately estimate the preference of students and the objectives of schools. Using the estimated model, I investigate the welfare effects of expanding charter school capacity, a hotly debated policy in NYC. Results show that the spillover effects are substantial and the heterogeneity is large. The welfare effects for Black and Hispanic students are large and positive for those who get enrolled in charter schools, but the indirect welfare effects induced by public school horizontal adjustments are negative for them and partially offset the gains from expanded charter school enrollments. For White and Asian students, the direct welfare effects are small, but the overall welfare increases due to positive spillover effects. Overall, the expansion of charter schools has positive spillover effects, but some groups with disadvantaged socio-economic backgrounds may have welfare loss. In Chapter 3, I quantify the effects of automobile franchising laws on US automobile dealer networks. I show that the US brand automobile manufacturers would like to have a smaller dealer network in absence of regulations. Building up the moment inequality approach, I estimate a static entry model with unobservable firm and market heterogeneity, where US automobile manufacturers are restricted in closing dealers. The counterfactual results show that US manufacturers would like to close about 28% of existing dealers if they are not restricted by government regulations. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]