Objectives: This study examined effects of a social intervention on depressive symptoms, melancholy, loneliness, and perceived togetherness in community-dwelling Finnish older people. Method: Promotion of mental well-being in older people (GoodMood; ISRCTN78426775) was a single-blinded randomized control trial lasting 1.5 years. Two hundred and twenty-three persons aged 75–79 years reporting symptoms of loneliness or melancholy were randomized into intervention and control groups. The intervention group was allowed to choose among supervised exercise, social activity, or personal counseling. Follow-up measurements were conducted at the end of 6-month intervention, and at 3, 6, and 12 months post intervention. Results: Number of depressive symptoms remained unchanged, while loneliness and melancholy decreased in both the intervention and control groups during the study (p<0.001). Social integration increased in the intervention group but not in controls (p=0.041). Attachment and guidance increased in both groups (p<0.001). Conclusion: The intervention did not alleviate depressed mood. Positive changes over time were observed in loneliness, feelings of melancholy, attachment, and guidance but these occurred independently of the intervention. Our secondary analysis suggests that the intervention increased perceived social integration. In sum, the effects of the intervention were moderate only and did not expedite further overcoming depressive mood or loneliness.