"Knowing the patient" is an essential element of nursing practice. Despite a key finding in prior studies, few scholars have directly inquired about the meaning of knowing the patient with nurses. We aimed to describe the meaning of knowing the patient and investigate how nurses obtain the information needed to support knowing the patient. A descriptive qualitative study was conducted with 12 nurses caring for pediatric patients on intensive care units. Nurses described knowing the patient as knowing clinical and personal information for individualized care. Verbal, paper-based, and electronic information sources were used to gather information needed to know the patient. The use of a paper-based supportive tool was the most valuable information source for nurses to know their patients. Future studies must further investigate the use of these paper-based tools and offer electronic solutions to support nurses in knowing their patients.