The purposes of this study were to develop an effective manual for the early self detection of depression in the Thai elderly, to detect the comorbidity of depression (pattern of drug and alcohol abuse, suicidal idea) and to ascertain the quality of life. A quasi experimental field research methodology (Randomized Control Group Pretest-Posttest Design) was implemented. The sample consisted of 1,390 elderly people in 35 communities from 4 districts surrounding Siriraj Hospital-Bangkok Noi, Bangkok Yai, Taling Chan and Bang Phlat. These areas are the peripheral parts of Bangkok and most of them have extended families. The result showed that: 1. The internal consistency reliability of the nine criteria of the manual for the self detection of depression in the Thai elderly ranged from 0.84 to 0.94. The validity tested by epidemiological methods, disclosed that the sensitivity was 82.14 per cent and the specificity was 97.56 per cent. 2. There was a statistically significant difference in the incidence of depression between the study and the control group (p<0.000); self referred cases = 86.7 per cent and 9.8 per cent respectively. The study group was able to detect depression in 42 days, while the control group did so in 122 days. In addition, in the associated comorbidity, there were differences in the patterns of drug and alcohol abuse, suicidal ideas and quality of life after the experiment. These findings showed a decreasing pattern of self medication for depression, and suicidal ideas and an improvement in the quality of life in the study group.