Accumulating research shows that gratitude exercises are effective for improving well-being but the pattern of results also suggests that moderators are likely at play. Researchers have begun investigating moderators of gratitude exercise impact but it remains unclear which are most important. To help clarify this issue the present study investigated trait gratitude baseline depressive symptoms and inclusion of a rationale as moderators of the efficacy of a two-week gratitude list exercise compared to a daily events list control condition. Results revealed that the gratitude exercise decreased depressive symptoms among participants high in such symptoms at baseline and eliminated the negative effect of low baseline trait gratitude on later happiness positive emotions and depressive symptoms. Implications limitations and future directions are discussed.