This study investigated comprehensive science teaching belief systems and their relation to science teachers' pedagogical content knowledge and teaching practices. Rokeach's (1968) belief system was used as a framework for representing the hierarchy among in-service teachers' teaching beliefs. This study employed a multiple case study design with three in-service science teachers. Cases were selected based on participant's personal epistemology. Data were collected through interviews and classroom observations. Content analyses showed that when science teachers presented characteristics of autonomous self-construal more than related self-construal, they had a more advanced personal epistemology. In addition, these beliefs shaped participants' conceptions of teaching and learning science as well as self-efficacy beliefs, knowledge and practice. Given these results, it is important for social psychologists to collaborate with science teachers to support their self-construal.