The authors find justification for integrating science, technology, engineering, and mathematics (STEM) in the complex problems that today's students will face as tomorrow's STEM professionals. Teachers with individual subject-area specialties in the STEM content areas have limited experience in integrating STEM. In this study, the authors investigated the conceptual changes of secondary school teachers teaching domain-specific STEM courses after a week-long professional development experience integrating earthquake engineering and domain-specific concepts. They documented and then triangulated outcomes of the experience using participating teachers' concept maps and teacher-generated written materials, respectively. Statistical comparisons of participants' concept maps revealed significant increases in their overall understanding of earthquake engineering and more accurate linkages with and among science domain-specific concepts. Content analyses of teachers' learning products confirmed the concept map analysis and also provided evidence of transfer of workshop learning experiences into teacher-designed curriculum products accurately linking earthquake engineering and domain-specific STEM content knowledge.