Abstract: Researchers have shown that about 40 % of our happiness is accounted for by intentional activity whereas 50 % is explained by genetics and 10 % by circumstances (Lyubomirsky, Sheldon & Schkade, 2005). Consequently, efforts to improve happiness might best be focused in the domain of intentional activity: willful and self-directed activity (Sheldon & Lyubomirsky, 2007). Such activity is nested in the “sustainable happiness model ” proposed by Lyubomirsky, Sheldon, and Schkade (2005) which states that happiness is in part within our ability to manage. Earlier work (Fordyce, 1977; 1983) supports the premise that individuals can sustain levels of happiness through volitional behavior. The current pilot study explored one such intentional activity – composing letters of gratitude. It was hypothesized that writing three letters of gratitude over time would enhance important qualities of subjective well-being in the author; happiness, life-satisfaction, and gratitude.