This study aims to develop an indigenous science instructional model. The samples were divided into two groups. Firstly, 24 experts for designing an indigenous science instructional model using Delphi Technique. Secondly, three classrooms of Mathayomsuksa 3 students for developing an instructional model. The findings revealed that Delphi technique provided ways to promote science learning through local culture and to develop student abilities. Also, the LADDA Instructional Model (Learning, Analyzing, Deciding, Doing, and Application) gained higher post-test scores in science learning achievement, values of science-culture in accord, and environmental conservation behavior than the pretest scores. (Contains 1 table.) [This paper was published in: ICER 2007: The 1st International Conference on Educational Reform Proceedings (Mahasarakham University, Thailand, November 9-11, 2007), pp329-240.]