During an ethnography conducted in an intensive care unit (ICU), we found that anxiety and agitation occurred frequently and were important considerations in the care of 30 patients weaning from prolonged mechanical ventilation. We conducted a secondary analysis to (a) describe characteristics of anxiety and agitation experienced by mechanically ventilated patients, (b) explore how clinicians recognized and interpreted anxiety and agitation, and (c) describe strategies and interventions used to manage anxiety and agitation with mechanically ventilated patients. We constructed the Anxiety/Agitation in Mechanical Ventilation Model to illustrate the multidimensional features of symptom recognition and management. Patients' ability to interact with the environment served as a basis for identification and management of anxiety or agitation. Clinicians' attributions about anxiety or agitation, and "knowing the patient," contributed to their assessment of patient responses. Clinicians chose strategies to overcome either the stimulus or the patient's appraisal of risk of the stimulus. This article contributes to the body of knowledge about symptom recognition and management in the ICU by providing a comprehensive model to guide future research and practice.