The European Court of Human Rights (ECtHR) has been the subject of extensive scholarship in the field of comparative judicial politics, recognized for its significant role in domestic rights protections. The literature has additionally theorized that amicus curiae at the Court can influence how judges decide cases, and suggests that participation may offer a means for engagement in the Court’s rule-making. The question I examine is how organizations and advocacy groups at the ECtHR have shaped the interpretation and implementation of the Convention. I analyze 153 cases from 1983-2019 involving refugees and asylum seekers, coding judgments for key variables to track third-party interventions and NGO communications. I also draw from a study of the ECtHR’s case law concerning unaccompanied migrant minors. Preliminary findings suggest that interventions are focused on advancing claims pushing for the Court to rule certain violations, and importantly can shape the Court’s decision-making. The data also indicates that information submitted by NGOs are evaluated and adopted by the Committee of Ministers during the implementation of judgments. These findings suggest that human rights organizations and advocacy groups can shape the interpretation and implementation of the European Convention through participation.