The purpose of this research is to find the effectiveness of the instructional packages in Thai language reading comprehension, according to the requirements of 80/80, for the third grade primary students of Thai Christian School, Bangkok; and to compare their results of learning of pre - test and post - test scores with the instructional packages. The research sample group was the purposive sampling; that is, the third grade primary students Thai Christian School, in 1st semester of 2008 which consisted of 24 students (one classroom). This research took two weeks (six hours per week). The research tools used for collecting data were the lesson plan, the instructional packages in Thai language reading comprehension and  the test. The method used for analyzing the data were percentage, average, dependent sample t-test.
	The results of this research was found that the effectiveness of the instructional packages in Thai language reading comprehension was at 86.61/83.23 which was accordable to the requirements of 80/80.  Morever, the students who learnt with these instructional packages got significantly higher average post-test scores than pre-test at 0.01 level. 
