Your medical practice has an existing culture that manifests itself daily in literally hundreds of ways. Some aspects of your culture likely support your practice's growth; others may be impeding your progress. This article describes the characteristics of medical practice culture and provides numerous examples of how culture influences behavior. It describes how culture is expressed in a medical practice through objects and artifacts, language, emotions, interactions, practice management systems, and daily work habits. It offers three techniques for assessing an existing medical practice culture and a checklist for conducting culture observations. This article also provides guidelines for identifying a desired medical practice culture and explores why changing culture is so difficult. It describes five reasons employees are likely to resist culture change and provides 12 fundamental changes that will enable a practice to improve its culture. Finally, this article explores how medical practice cultures are formed and perpetuated and provides more than a dozen questions to ask employees in a culture survey.