The purpose of the study is to investigate the effect of e-Learning course for kindergarten teachers and to generate suggestions for the revision of the course and other future e-learning courses similar to the course. To pursue for the purpose of the study, the researcher conducted two interdependent studies: a quantitative study that tested overall effect of the treatment, and a follow-up qualitative study that further investigated the possible reasons of and solutions to the results found from the quantitative study. Two hundred and ninety two subjects had participated in the quantitative study, and sixteen subjects selected from the 292 were invited to the qualitative study. The results indicate that the most attractive features of the e-learning course were 1) the quality of the contents provided and the tele-presence of authoritative lecturers, and 2) the any-time, any-where functionality of technology-based learning opportunity. Follow-up qualitative analysis revealed major findings that describe the reasons underlying the results. Also some issues that should bring some concerns such as the flaws of measurement instrument were discussed. Finally, implications regarding instructional design of e-Learning courses were suggested. Key words: effectiveness of e-learning, instructional design, case study, kindergarten teachers training