This issue of Ultrasound Clinics  explores the role that ultrasound plays in diagnosing and treating common disorders of the head and neck. Future applications of ultrasound technology are also discussed. Articles in this issue include "Head and Neck Ultrasound: Why Now?; Ultrasound physics in a nutshell; Head and Neck Anatomy and Ultrasound Correlation; Interpretation of Ultrasound; The Expanding Ultility of Office-Based Ultrasound for the Head and Neck Surgeon;The Role of Ultrasound in Thyroid Disorders; Techniques for Parathyroid Localization and Ultrasound;Ultrasound-Guided Procedures for the Office; Head and Neck Ultrasound in the Pediatric Population; and Emerging Technology in Head and Neck Ultrasonography.