This paper presents the findings of an exploratory case analysis of three beginning social studies teachers regarding how their personal theorizing impacted their instructional decision making and classroom actions as newly inducted teachers. In addition, how the teachers' personal theorizing evolved as a result of their first year of experience is also presented. During their pre-service experiences, the teachers identified an operational set of personal practice theories (PPTs) that guided their respective practices. The PPTs were used as the theoretical constructs from which to determine the relationship between personal theorizing and practice. The findings indicate that each teacher attempted to utilize their PPTs to guide their first year of teaching. Furthermore, for two of the three teachers, their PPTs largely impacted their instructional decision making. Finally, all three individuals experienced further development and refinement of their instructional beliefs as a result of their first year of teaching. Two of the three teachers continuously refined their PPTs in an effort to improve practice, while the third teacher developed a new set of instructional beliefs to fit her given instructional setting. (Contains 20 references.) (SM)