What has competition got to do with gender? Competition authorities play a crucial role in shaping fair and thriving markets. However, the connection between competition and gender is often overlooked. This Toolkit equips competition authorities with the knowledge and tools necessary to incorporate gender considerations into their work. The Toolkit offers an evidence-based approach, going beyond theory to provide concrete recommendations that can enhance the accuracy of analysis, facilitate cartel investigations and optimise advocacy efforts. Drawing from gender research in related policy areas such as corporate governance, anti-corruption, and behavioural economics, this Toolkit provides a comprehensive framework for integrating gender considerations. By incorporating this Toolkit into their day-to-day operations, competition authorities can contribute even more to the advancement of fair and efficient markets that benefit individuals of all genders.