An emerging critique of theoretical explanations of legal mobilization that focus on legal opportunity structures alone is that they tend to treat litigants as if they were black boxes. In doing so they ignore the internal political and material struggles of litigant groups as well as the inter-organizational dynamics that might influence whether any single organization will turn to the courts. This panel will focus on research at the micro-level that focuses on the private agents of legal mobilization themselves as well as research that explores their relationships with each other and with state institutions. This panel will include papers that  ask why such private actors litigate in the first place and explore micro-level explanations that have been identified in the existing literature as important potential agent-level explanatory variables in accounting for differentiated legal mobilization propensities: organizational perceptions and preferences; resource mobilization; identity politics and relational issues. The final paper in the panel will conclude by providing a synthesis of system level and actor level explanations of variation in European legal mobilization.