Preface The role of the clinical pharmacist has evolved significantly over the past decade, with California helping lead this transformation. In 2013, Senate Bill 493 expanded the pharmacist's role as a healthcare provider and established the Advanced Practice Pharmacist (APP) recognition. In 2026, Assembly Bill 1503 updated the terminology from Advanced Practice Pharmacist to Advanced Pharmacist Practitioner, reflecting the continued advancement of pharmacists as active members of the healthcare team. In 2020, Wynn Medical Center began a pioneering collaboration with the University of Southern California, 986 Pharmacy, and later Western University to develop an Advanced Pharmacist Practitioner residency program. The program was created to train PharmD residents to practice in a physician-led clinic setting, where they can contribute directly to primary care, chronic disease management, medication optimization, patient education, and interdisciplinary care. This guide is designed to provide Advanced Pharmacist Practitioners and APP/PharmD residents with a practical foundation in 350 common conditions encountered in primary care. Organized across 24 chapters, the book covers the APP profession, major internal medicine disorders, common conditions in pregnancy and pediatrics, post-surgical and wound care, laboratory and imaging interpretation, biostatistics, and preventive care. I extend my heartfelt gratitude to the international team of expert reviewers, editors, students, and contributors whose dedication, insight, and expertise made this textbook possible. Huynh Wynn Tran, MD, FACP Associate Professor of Medicine and Pharmacy Founder/CEO of Wynn Medical Center Clinics and IPA Los Angeles, California, USA