This study evaluated the effectiveness of Aprendo Leyendo, a structured literacy program, by comparing reading outcomes of first- and second-grade students in intervention schools with those receiving business-as-usual instruction in control schools. Teachers in intervention schools received 40 hours of professional development and ongoing coaching support over two school years. Student reading performance was assessed at multiple time points using standardized Spanish-language literacy measures to examine growth over time. The study was conducted in 15 schools in Buenos Aires, Argentina.