[en] The massive integration of electric vehicles (EVs) can pose challenges for electricity systems if charging is not appropriately managed. However, EVs can provide flexibility, improving system operation, by using smart charging and discharging strategies. This thesis studies EV integration into distribution systems through technical, behavioral, economic, and regulatory aspects. First, the use-cases for flexibility at the distribution level are identified, along with the remaining technical, economic, and regulatory barriers for their deployment. Second, an assessment of the impact of plug-in behavior (i.e., users not plugging in every day) in EV integration studies was carried out. For this, an agent-based model was developed and calibrated with real-world data. The impact of EV charging and EV fleets' potential to provide flexibility are evaluated and consequences of current trends towards larger battery sizes are derived. Third, a framework to assess EV charging impact in realistic medium voltage grids that considered granular open-source datasets was developed. We evidenced the impact that local mobility patterns (rural vs. urban) and spatial distribution of EVs have on EV grid integration and its coupling with distributed renewable generation. Finally, we studied market mechanisms to procure flexibility at the local level implemented by European distribution system operators. Using a regulatory analysis framework, barriers to entry for EV aggregators were identified, and a case study to assess the potential revenues of different types of EV fleets participating in these schemes was carried out. Policy recommendations for market design were derived. (author)