Studies in science education literature outline the impediments to successful integration of inquiry into school science. In order to fully understand the issues regarding successful integration of inquiry into school science, researchers point out the need to further study teachers' characteristics and use of inquiry in local context. The purpose of this multiple case study is to add on the literature that is aimed at understanding teachers' inquiry beliefs and the factors that influence the teachers' ability and willingness to incorporate inquiry into their science instruction. The participants of this study are practicing teachers who were accepted into a science education Masters Program at a southern university in the US. Findings of this study indicate the following as threats to the integration of inquiry into school science: (1) teachers' lack of strong content knowledge and inquiry science experience; (2) teachers' approaches to initial implementation of inquiry in their classrooms;(3) teachers' mixed feelings about the assessment of Inquiry Learning; (4) over-emphasis on standardized tests; (5) lack of teacher-teacher collaboration and administrative support; and (6) lack of student readiness for inquiry learning.