Objective: We investigate the applicability of the Big Five model in rural Southeast Asia and thereby challenge recent concerns about the validity of the model in developing countries. Method: We use a novel data set on personality traits from rural Thailand and Vietnam (N = 3811 individuals). In our analysis, we (i) assess the factor structure of the data, (ii) test the internal consistency of the items, (iii) compare the traits across two consecutive survey waves, and (iv) employ regressions to demonstrate the economic relevance of the traits. Results: The results demonstrate a five-factor structure that fits the Big Five model. We observe changes in personality traits over time but Cohen's d coefficients only range between 0.06 and 0.21. The average rank-order stability, measured by the test–retest correlation of the Big Five between the two consecutive waves, lies at 0.21. Individual changes in personality traits over time relate to experienced shocks and appear to be largely independent of age, gender, and education. We further find that openness and emotional stability positively correlate with rural incomes. Conclusions: While there is skepticism, pertaining to the use of personality trait models in developing countries, our study demonstrates that their importance and usage cannot be rejected.