["Sociological Forum, EarlyView. ", "\nABSTRACT\nThis study examines how protest episodes foster political efficacy among ordinary citizens. Based on 44 in‐depth interviews with participants in two major 2018 mobilizations in Spain—the feminist strike of International Women's Day and the pensioners' protests—the analysis identifies discursive expressions that reflect attitudinal change across three dimensions: cognitive, agentic, and collective. These include increased political attentiveness, feelings of empowerment, and renewed belief in collective action. Notably, these expressions often combine in participants' narratives, suggesting a dynamic interplay between efficacy dimensions that reinforces perceptions of political agency. The study highlights three key mechanisms behind these transformations—exposure to reliable information, vicarious learning, and shared mastery experiences—that nurture both individual and collective efficacy. The analysis shows that the specific forms of efficacy change are shaped by both the nature of the protest episode and participants' prior protest experience, with first‐time participants displaying the most varied changes. These findings underscore the transformative potential of emotionally resonant protest episodes. Far from being trivial or symbolic, even low‐cost protest episodes may function as socially embedded learning environments.\n"]