Regional Trade Agreements (RTAs) have become the major route for countries to reduce trade barriers and open new markets. To fully assess the current state of market opening for agricultural products and examine the potential impacts of RTAs, access to up-to-date and consistent information on preferential tariffs is crucial. There are multiple databases that collect information on preferential tariffs; however, it is not always easy to identify how these databases differ in terms of their data collection, treatment and representation, nor which database is the most appropriate for a specific type of analysis. This practical guide aims to help trade negotiators, policy makers, researchers, and private sector actors to identify which international or national database to use for their analysis of preferential tariffs on agricultural products.