What does it mean to understand an utterance? What are the conditions? How can one observe whether an utterance has been understood, in the way the speaker intended or in another way? How can differences between speaker-intention and hearer-intention be judged? A functional approach to the hearer-aspect of linguistic communication, including chapters on: hearer conditions on successful communication; convention and culture; effects of speech acts as a dimension in describing the process of understanding; and conditions of understanding in non-native communication.