Abstract: As it has been developed over a period of many decades, administrative law has acquired its own morality, closely related to what Lon Fuller described as the internal morality of law. Reflected in a wide array of seemingly disparate doctrines, but not yet recognized as such, the morality of administrative law includes a set of identifiable principles, often said to reflect the central ingredients of the rule of law. An understanding of the morality of administrative law puts contemporary criticisms of the administrative state in their most plausible light. At the same time, the resulting doctrines do not deserve an unambiguous celebration, because many of them have an ambiguous legal source; because from the welfarist point of view, it is not clear if they are always good ideas; and because it is not clear that judges should enforce them.