This course provides physician assistant students with focused instruction in the appropriate selection and interpretation of clinical diagnostic testing, with emphasis on evidence-based decision-making in the primary care setting. Course delivery includes assigned readings, online materials, instructional videos, and weekly lectures. Formative in-class activities reinforce critical thinking skills and support the integration of learned material into clinical decision-making. Instruction begins with an introduction to evidence-based medicine and clinical diagnostic concepts before progressing to an in-depth system-based format. Content complements and reinforces learning in the Clinical Medicine and Clinical Skills courses, establishing a strong foundation for advanced coursework, supervised clinical experiences, and evidence-based patient care. The course supports the acquisition of program-defined competencies through the development of medical knowledge, clinical reasoning, and problem-solving skills essential for safe, effective, and patient-centered practice.