This article uses philosophical inquiry to present the relationship between the helping role in nursing and the concept of trust essential to it. It characterizes helping as the moral center of the nurse-patient relationship and discusses how patients' expectations of help and caring create obligations of trustworthiness on the part of the nurse. It uses literature from various disciplines to examine different theoretical accounts of trust, each presenting important features of trust relationships that apply to health care professionals, patients, and families. Exploring the concept of trust, and the key leverage points that elicit it, develops a thesis that nurses can improve their understanding of the principal attributes and the conditions that foster or impede trust. The article concludes that trust is the core moral ingredient of helping relationships. Trust as a moral value is even more basic than duties of beneficence, respect, veracity, and autonomy. Trust is the confident expectation that others can be relied upon to act with good will and to secure what is best for the person seeking help.