Motivation: Much of the world's population still lacks access to safe drinking water and sanitation, particularly people living in poverty and in rural areas. The literature suggests that lack of access to water, sanitation, and hygiene (WASH) contributes to poor development of young children. That further leads to inadequate cognitive stimulation, stunting, iodine and iron deficiency, and lower productivity. Purpose: We aim to study the status of early childhood health in Indonesia by measuring an Early Childhood Health Index and to examine the role of access to safe water, sanitation, and hygiene in improving children's health using the national representative data of Indonesian Family Life Survey (IFLS) waves 4 (in 2007) and 5 (in 2014). Methods and approach: Our methodological approach consisted of two steps. First, we developed WASH Index and Early Childhood Health Index using polychoric Principal Component Analysis (PCA), then assessed the association between the two indices using Ordinary Least Squares (OLS) regression. Findings: Overall, we found significant associations between the WASH Index and children's health status and nutritional status. The results also show that several important indicators of WASH (in particular, quality of drinking water, washing and bathing water, and sanitation) improved between 2007 and 2014. Children's access to health care and several children's health indicators also got better. Nevertheless, we still observed stable conditions or even worsening conditions in other components, namely an increase in stunting and children's morbidity. Policy implications: This study provides evidence that access to safe drinking water, sanitation, and hygiene is essential to improve children's health status. In accordance with Government Regulation of the Republic of Indonesia number 185 from 2014, the government at the national, provincial, and district levels must accelerate the development of public infrastructure to ensure access to safe drinking water, sanitation, and hygiene for the entire population as this investment is essential to improve young children's health and reduce the prevalence of stunting in Indonesia.