The velopharyngeal (VP) port separates the nasopharynx from the oropharynx and is bordered by the velum, lateral pharyngeal walls, and posterior pharyngeal wall. Velopharyngeal dysfunction (VPD) is the inability to achieve proper closure of the VP port, affecting speech and swallowing. This 3-part series provides a comprehensive discussion on (1) the anatomy and physiology of the velopharyngeal mechanism; (2) fundamental speech terminology and principles of perceptual speech assessment for VPD; and (3) techniques for objective evaluation of the VP port and surgical decision-making process. In part 1, the authors focus on the anatomy and physiology of the velopharyngeal port, the anatomy of cleft palate, and the causes of VPD. There are 3 types of VPD: velopharyngeal insufficiency, involving structural deficits; velopharyngeal incompetence, resulting from neuromuscular issues; and velopharyngeal mislearning, due to maladaptive speech habits. VPD is commonly associated with cleft palate due to anatomic disruptions that impair velopharyngeal function. However, there are numerous causes of noncleft VPD, including congenital or acquired structural defects, neuromuscular conditions, and developmental/behavioral factors. Diagnosis and management of VPD require a multidisciplinary approach involving, at a minimum, surgeons and speech-language pathologists. Plastic surgery trainees often receive education on the surgical treatment of VPD, but without a foundational knowledge of the disease spectrum and speech pathology, the complex terminology can impede a thorough understanding of its diagnosis and management. This series serves as an accessible resource, providing the foundational knowledge required for surgical trainees new to this topic.