This thesis studies the impact of policy changes and technological progress on economic growth and inequality. The first chapter studies the impact of intellectual property rights protection policies on firms\u27 boundary and innovation choices, and economic growth. This chapter shows specialization patterns of US firms in the 1980s and 1990s. Specifically: 1) Firms, especially innovating ones, decreased the number of industries in which they produce. 2) Small firms increased innovation intensity while large firms decreased it. A new hypothesis is proposed, highlighting the role of pro-patent reforms that make firms\u27 innovations more tradable. An endogenous growth model with firm heterogeneity is developed. Calibrating the model suggests...