The salience of early childhood education for the vulnerable is widely recognized but its
compensatory effect is suspicious in Korea. A series of studies, showing the effective change of
children's development through noncognitive ability, provide new direction different from earlier
documents focusing on enhanced social status via academic achievement. Investment in the
vulnerable children, only ever considered through a social equity perspective, is another way to
simultaneously achieve social efficiency since the investment for the vulnerable potentially
mitigates the social costs incurred by them. The purpose of this study is to examine the
do-run-do-run project which is invented for social, emotional, and language development of the
socioeconomically vulnerable children. This sets up non-equivalent comparison group design
which includes the characteristic of the social experiment. This study applies a
difference-in-difference method which compares difference before and after treatment in
adjusting difference of control and treatment group to remove individual infant's traits. The
result shows that do-run-do-run program significantly increases children's social and language
ability. However, the increasement does not rise to median level. This may indicate that
strengthening of the program input is necessary. This study theoretically provides an effect of
early childhood intervention on the socioeconomically vulnerable children and practically
provides a model, data gathering, and procedure for causal analysis. Lastly, the fact that
civilian's volunteering activity makes program effective signifies that it successfully compensate
for public welfare in an era lacking in public welfare resources.