My dissertation studies the impact of globalization on firms and workers. In chapter 1, I examine how import competition affects multi-product firms utilizing the concept of 'core competency'. I find that: (i) a rise in imports of core product lead the firm to divest the peripheral products and refocus to the core, and (ii) the stronger the complementarities that a peripheral product shares with the core (as measured by the extent of joint sales, joint procurement and joint production), the less likely is the peripheral product to be divested in response to import competition. In chapter 2, I link unaffiliated cross-border service data and matched March Current Population Survey data to estimate the impact of service offshoring and inshoring on earnings changes, probability of switching industry and probability of switching occupation for U.S. workers, especially for highly-educated workers and skilled white-collar workers. I find statistically significant evidence that U.S. workers are more likely to switch industries (occupations) as their industry (occupation) exposure to service offshoring to low-wage countries increases. I also find statistically significant evidence that earnings growth increases and probability of occupation switch decreases as U.S. exports more services to low-wage countries. However, both the costs of offshoring and the benefits of inshoring are economically small. In chapter 3, I investigate the impact of low-wage import competition on worker reallocation within U.S. manufacturing industries. By using a matched panel of workers drawn from consecutive monthly Current Population Surveys during 1992-2001, I examine how low-wage imports affect job insecurity and instability and how various cohorts of workers respond to import shocks differently. I find that the probability of unemployment as well as industry switch and occupation switch are positively associated with industry exposure to imports sourced from low-wage countries for the U.S. manufacturing workforce. In addition, I find that the costs of low-wage import competition are borne primarily by high-school dropouts or unskilled blue-collar workers.