The purpose of this study was to develop Thai cluster pronunciation exercises (the efficiency standard level of 80/80), and to compare the effectieness between the experimental group and the control group.  The population was  90 students in the second semester of the 2007 academic year, Prathomsuksa Two, Bilingual Program, Thai Christian School, Bangkok. 
 	The research instruments used ware the six Thai cluster pronunciation exercises, the learning plan, and the achievement test.  The statistics used in analyzing the data was mean, percentage, standard deviation (t - test) 
 	Findings from the study showed that 1) the pronunciation of Thai clusters before and after the experiment in the first, second, third, fourth, fifth and sixth exercises had an efficiency value of 87.13/86.67, 90.13/90.00, 87.68/92.33, 87.20/83.33, 90.67/90.00 and 89.80/89.67  2) The comparison of the experimental group in pronouncing Thai clusters before and after the experiment was significantly different at .05 level.  The post test scores were higher than the 
pre test scores at 21.03 and 27.95.  3) The comparison between the experimental group and the control group, the pronunciation of Thai clusters after the experiment was significantly different at .05 level.  The post test scores were higher than the pre test scores at 27.97 and 24.13.
