BACKGROUND: As the bio-regulatory principles (Dosha) are the essential components of the body, the three attributes (Triguna)-Satva, Raja, and Tamas are the crucial components of the mind that determine an individual's mental status. Though Triguna-based psychological assessment tools are available, there are no standardized tools to evaluate mental health using this unique Ayurvedic approach.So this research was undertaken to create a simple, self-administering instrument for screening mental health based on Ayurvedic concept-Triguna. OBJECTIVE: To develop a simple, reliable, and valid self-administering instrument based on Triguna concept of Ayurvedic classics for screening mental health. METHODS: Standard steps to develop the instrument -Conceptualization, item generation, item selection, item wording, Translation-back translation, pre-test, pilot study, Test-retest were done before the final administration of the draft instrument. Reliability and validity testing were carried out. Reliability assessment included Test-retest and internal consistency. Face, content, construct, criterion and convergent validity were done as part of the validity assessment. Exploratory factor analysis using Principal Component Analysis with Varimax rotation was employed for construct validation and item reduction. A cross-sectional study employing a stratified, multi-stage cluster sampling technique was conducted among 400 participants aged 20-40 years, representing rural, urban and coastal areas of Thiruvananthapuram, Kerala, India. The criterion validity of the newly developed tool was assessed against the WHO Subjective Well-being Inventory(SUBI).The reference standard, evaluated for its diagnostic properties including sensitivity, specificity, predictive values, and likelihood ratios, was administered alongside the draft instrument. After appropriate analyses, a 38-item self-administering instrument was developed and named as Mental Health Assessment Scale with Triguna (MHAS-TG). Hypothesis validation and construct validity were assessed using diverse community samples, comprising 100 individuals from various geographical areas of Kannur District, 100 students from NIT Calicut (Kozhikode) and 50 ex-convicts from Kannur District. RESULTS: The newly developed 38-item Mental Health self-Assessment Scale with Triguna (MHAS-TG) is presented as a discriminating tool that showed high Test-retest (Intra Class Correlation coefficient - 0.8) and Internal consistency reliability (Cronbach's alpha = 0.9). The tool had adequate face validity and content validity (Content validity index- 0.84). Construct validity by Exploratory factor analysis yielded 38 items of 9-factor solution with a cumulative variance of 58.06 %. The self-administering tool with a score range of 0-114 derived a cut-off score of 40 and 80 based on sensitivity and specificity. The scores below 40 were designated as poor mental health, 41-80 were assigned with moderate mental health, and score above 81 were designated with good mental health. Receiver operating characteristic curve analysis showed a Sensitivity of 75.36 % and a Specificity of 78.18. The average administration time of the tool was 10 min. Mental health screening of 400 individuals in Thiruvananthapuram district, Kerala, India yielded the following results: 28.25 % exhibited good mental health, 63.5 % had moderate mental health and 8.5 % had poor mental health. Re-validations at Kannur district showed 17 % with good mental health, 75 % with moderate mental health and 8 % with poor mental health. In Kozhikode, 16 % had good mental health, 74 % had moderate mental health and 10 % had poor mental health. In ex-convicts, 8 % had good mental health, 67 % had moderate mental health and 25 % had poor mental health. Independent t-test showed that there was a significant difference (p < 0.05) between the two score values. On analysis a weak positive correlation (p < 0.01) was seen between Satva and Rajo Guna scores, a strong negative correlation (p < 0.01) between Satva and Tamo Guna and a moderate positive correlation (p < 0.01) between Rajo and Tamo Guna. CONCLUSION: MHAS-TG is a 38-item tool, valid and reliable self-administering instrument based on Triguna concept. The proposed tool with risk and protective factors affecting mental health is a quick and easy screening tool for assessing mental health.Administration of the tool to 400 participants in Thiruvananthapuram district revealed its ability to identify individuals with poor mental health. The results also showed a weak positive correlation between Satva-Rajo scores, a strong negative correlation between Satva-Tamo scores and a moderate positive correlation between Rajo-Tamo scores.