Can you disagree with someone without thinking that what they say is false? As we shall see, this is not only possible but quite frequent. Starting with the type of disagreement most familiar from the philosophical literature, we will progressively expand the circle of genuine disagreement until it encompasses even conceptual disagreement, which might sound like a contradiction in terms. For conceptual disagreement necessarily involves the parties' using different concepts, which one might think would preclude genuine disagreement. We shall argue (...) otherwise, adducing three different types of case in order to demonstrate the scope of this phenomenon. (shrink)