This study introduces the Cooperative Catalyst Method (C2M), an instructional approach designed to support interdisciplinary learning through cooperative learning and social constructivist principles. In C2M, trained students act as catalysts who facilitate peer learning within heterogeneous groups. The method consists of four stages: selecting catalysts, forming groups, identifying disciplinary subtopics, and implementing instruction, with assessment conducted through tests and interviews.The study demonstrates the application of C2M in Chemistry, Social Studies, Geography, and Science courses using interdisciplinary topics such as gases, climate change, weather phenomena, and force and motion. By promoting active participation, collaboration, individual responsibility, communication, and critical thinking, C2M aims to improve academic achievement, conceptual understanding, knowledge retention, and interdisciplinary thinking. The findings indicate that C2M provides a flexible and effective framework for meaningful learning in contemporary education.