This study aims to investigate happiness in 4 and 5 years old children and the relative effects of various factors including the personal factor (ego-resiliency), the family relation factor (family strength), and early childcare factor (facility adjustment to early childhood institution). Participants were 154 children ages 4 and 5 who attend childcare centers as well as their mothers and the 19 teachers in charge of them. Using SPSS 21.0 package, we conducted frequency analysis, descriptive statistics, Pearson’s correlation analysis, and multiple regression analysis to explore the questions raised in this study. Results demonstrated significant positive correlations between ego-resiliency, family strength, adjustment to early childhood institution, and children’s happiness. Children’s adjustment to the early childhood institution showed the largest explanatory power on the variance of their happiness, followed by ego-resiliency and family strength. Study results reveal the critical impact of smooth adjustment on the happiness of the children who attend these childcare centers as this factor was shown more powerful than strong personal and famaily relations. The results call for an enhancement of early childcare quality to heip ensure children’s happiness.