Objectives: To estimate socio-demographic factors and early life events associated with happiness in adults in metropolitan Lima. Materials and methods: A secondary analysis was carried out on the Epidemiological Study of Mental Health of Metropolitan Lima 2012. The instruments used were the Quality of Life Index; a brief and modified version of the EMBU; a questionnaire of early adverse events; a Happiness Index built from Andrews’ single item of Happiness and the Life Satisfaction Scale. Adjusted multivariate analyses were performed. Results: Happiness was significantly associated with gender, marital status, poverty, and level of education. Parenting styles associated significantly with less happiness were: behaviors of rejection and sexist attitudes; and with higher happiness: emotional warmth. No association was found with overprotection or favoritism breeding practices. Early adverse events significantly associated with lower happiness were discussions within the family, father with problems of alcohol, parental absence, behaviors of emotional blackmail or threats. Conclusions: This study highlights the importance of developing intensive programs in the first years of life that promote parenting styles and healthy development environments.