Background: Happiness is considered an index of the development of human society and well-being in the world. Aims: The aim of this study was to measure the level of happiness (LoH) in a middle sized Iranian city (Kerman) using 2 instruments and the predictor factors. Methods: In a cross-sectional study, 1000 adults were questioned using multi-stage cluster sampling in 2016. The LoH was assessed using the Oxford Happiness Inventory (OHI) and a self-report questionnaire. The level of physical activity and the religion index were assessed using standard questionnaires. Results: The results of 2 questionnaires had a statistically significant correlation with measuring LoH (Pearson correlation coefficient 0.69; P-value < 0.001). Around 90% of participants stated that they had moderate to high LoH, but the mean happiness score based on the OHI was 43.2 (43.7 in men, 42.7 in women). Illiteracy, unemployment, divorce, living in deprived areas, high level of stress, weak religious beliefs and practice, lower income, and poor health significantly 1 / 13 WHO EMRO | Levels and predictors of happiness in the south of the Islamic Republic of Iran decreased the LoH score. Conclusion: LoH is relatively low in Kerman. There are effective evidence-based interventions that might promote the LoH of the population, including promoting the level of community health, educating for stress management and improving access to urban facilities in deprived areas.