The participants of this study were derived from purposeful sampling, which is one type of the non-probability based sampling techniques. To elaborate, purposeful sampling avoids random sampling by targeting a specific group of people, often a small group rather than a more general one (Kerlinger, 1986). However, the sample derived from purposeful sampling is not easily defensible as being representative of populations due to potential subjectivity of researcher (Black, 1999). The main objective of this study is not to generalize the findings from a sample to a population, but rather to derive more information about NOS conceptions of science teachers from Thailand and Bangladesh reflected through MOSQ. The criteria for participants in this study were that they must be in-service science teachers, who are responsible for teaching in the secondary level in either Thailand or Bangladesh.