This study was to examine the effect of short-term study abroad program on Thai EFL high school students’ English vocabulary knowledge and their attitudes toward learning English. The participants were 17 high school students from Phuket Witthayalai school. The instruments used for data collection process were an English vocabulary test and questionnaires. Data analysis involved descriptive statistics including mean, standard deviation, and a t-test analysis.

           The results were as follows: 1) There were no statistically significant differences in SA students’ mean scores of vocabulary test between pretest and posttest However, SA students’ vocabulary scores of the posttest were higher than pretest scores (M = 13.29, SD = 2.62, p > .05). 2) Students’ attitudes towards learning English were higher comparing to the prior results before attending SA in non-statistically significant level (M = 4.35, SD = .43, p > .05). The findings pointed out that despite no significantly statistical differences were found in the results of this study, the short-term SA program had a positive effect in enhancing both Thai high school EFL students’ vocabulary knowledge and their attitudes towards learning English.