This is the first course in a two-part sequence. We study recent developments in empirical international trade and focus on estimation methods drawn from the field of empirical industrial organization. The reading materials include a mix of trade theory papers, empirical trade papers and industrial organization applications. The sessions will combine expositions by the lecturer, presentations by students and 'hands-on' coding, mostly in Matlab and Stata. We will start by studying the sources, implications and empirical patterns of heterogeneity across firms in international trade. Focusing on productivity heterogeneity, we will study approaches for estimating production function parameters, as well as supply-side approaches to recover heterogeneous markups.