The development of mental imagery in relation to the comprehension of concrete proverbs (e.g., "one rotten apple spoils the barrel") was examined in children, adolescents, and adults who were ages 11 to 29 years old (n = 210). The findings indicated that age-related changes occurred in mental imagery and in proverb comprehension during the years between late childhood and early adulthood, and that the two domains were associated in children and adults but not in adolescents. Children and adults were more likely to describe relevant mental imagery (age 11: "A big barrel of apples and a woman picks up one that is rotten and there are worms in it and the worms go to all the other apples") when they also comprehended the proverb on a multiple-choice task. It was also found that participants' mental images became more metaphorical in relation to increasing age (age 21: "One bad comment can spoil the entire conversation"). The findings are consistent with "dual coding theory", the view that nonverbal information (relevant visual imagery) in addition to verbal information (related words and phrases) supports language comprehension in the case of concrete meanings. The results also support the view that mental imagery reflects figurative understanding and the individual's tacit awareness of underlying metaphorical concepts.