The aim of the current study was to evaluate the impact of a 6-week gratitude intervention for people with low to moderate well-being and moderate symptomatology of depression and anxiety up to 6 months follow-up. 217 Dutch adults were randomly assigned to one of three conditions: a 6-week gratitude intervention, a 6-week self-kindness intervention as an active control condition and a waitlist control condition. Participants completed online assessments on well-being, depression, anxiety and gratitude at baseline, post-test, 6 weeks and 6 months follow-up.