The purpose of this study was to examine the mediating effect of social capital between informal
learning and team effectiveness. The data were gained from the D company which has team-based
systems. The response rate was 85.5%, 325 out of 380 surveys. For the analysis of this study, the only
312 surveys(the valid response rate 82.1%) but 13 incomplete ones were used. Baron and Kenny's(1986)
regression analysis was utilized in order to verify the mediating effects. In addition, Sobel test was used
to examine the statistical significance of the mediator effects. According to the results, all the three
components of social capital, trust, norms, and networks, was partially mediated in the relationships
between the informal learning and the team effectiveness. It proved that informal learning encourages the
formation of social capital and the social capital was involved in improving team effectiveness.
Consequently, this study showed that employees' commitment, attention, and satisfaction toward their
team increase when network, trust, and norm were formulated through team-based informal learning.
Based on these findings, the implications, the limitations, and the future study were suggested.