Alongside representation and legislation, scrutiny is a key responsibility of the local council and its councillors. This chapter analyses the scrutiny behaviour of local councillors across Europe. First, it presents councillors’ self-reported contributions to scrutinising the actions of the executive board, municipal policies, the budget, services, and external actors (including municipally owned corporations, inter-municipal cooperation, and other entities). Second, it maps how frequently councillors utilise different council tools for scrutiny and other activities. These tools range from informal questions and information requests to more formal and rigorous mechanisms, such as interpellations and inquiries. Lastly, the chapter seeks to explain the variation in the extent to which councillors monitor the government and employ council instruments. To do so, it employs a multivariate regression model that considers broader contextual factors (the municipal environment and local government setting), institutional capacity (formal and informal rules and support), and personal traits of councillors (attitudes and capabilities).