Abstract Based on two lines of research, a model is proposed to explain when individuals in a positive mood as well as individuals in a negative mood invest more or less effort in message processing. First, research has shown that moods affect likelihood estimates. That is, positive (negative) mood leads to a mood-congruent increase regarding the occurrence of positively (negatively) valenced events. Second, research has shown that mood-unrelated expectancies affect message processing. Combining both lines of research, I argue that mood-congruent expectancies also affect message scrutiny, that is, more effortful processing given expectancy disconfirmation rather than expectancy confirmation. This prediction was tested in two experiments involving initial information regarding source honesty and likability, respectively. As predicted, individuals in both positive and negative moods evinced more effortful message processing when initial information disconfirmed rather than confirmed expectancies. Thus, these results are consistent with a quite flexible view of individuals in both positive and negative moods regarding the effort invested in information processing.