While the role of lobbying in trade policy determination has been studied in a formal way since the early 1980s, it was the pathbreaking 1994 work by Grossman and Helpman in the following decade that led many scholars, using that framework (often with some modifications), to study many interesting political economy issues in the trade policy arena. Importantly, Grossman and Helpman were also the first to provide microfoundations to lobbying within a multisectoral, specific-factors framework. Moreover, the industry-level protection they derive is an empirically estimable function of measurable industry characteristics and other political and economic factors. With everything else held constant, organized sectors are able to obtain higher protection than unorganized sectors, with organized-sector protection inversely related to import penetration and import demand elasticity. Grossman and Helpman’s work gave an impetus to theory-driven empirical work in the political economy of trade policy, including the empirical investigation of the Grossman–Helpman model itself and its many extensions. There is now also a fairly large literature trying to explain the unrealistically high empirical estimates of the model’s parameters (representing the proportion of population politically organized and the weight the government attaches to aggregate welfare relative to political contributions). Extensions for empirical investigation that include bringing in competition between upstream and downstream lobbies, imperfect capturing of nontariff barrier (NTB) rents by the government, foreign lobbies, the possibility of misclassfication of sectors into organized and unorganized, and so forth partially correct the unrealistic parameter estimates. In addition, there are extensions that have been applied toward explaining policy changes and puzzles. Those extensions deal with lobby formation, trade agreements, unilateralism versus reciprocity in trade policy, lobbying for protection in declining industries, firm-level lobbying, the choice of policy instruments, and so forth. Despite so much work already done on lobbying and trade policy, the existing literature is deficient in the study of the choice of instruments, the antitrade bias in trade policy, and informational lobbying.