AN ABSTRACT OF THE DISSERTATION OF Frances Keller Shafer, for the Doctor of Philosophy degree in Curriculum and Instruction, presented on October 16, 2008, at Southern Illinois University Carbondale. TITLE: AN INVESTIGATION OF SELECTED FACTORS THAT INFLUENCE MIDDLE-LEVEL TEACHERS' PROFESSIONAL DEVELOPMENT CHOICES MAJOR PROFESSOR: Dr. Joyce Killian Professional development is defined as methods to provide teachers with the knowledge and skills to improve instruction and increase student achievement. However, the availability of and participation in professional development activities often falls short of meeting both the teachers' and students' needs. This study investigated selected factors that influence middle-level teachers' professional development choices. The purpose of this study was to add to the researcher's knowledge about professional development choices made by practicing middle-level educators and to add to the body of knowledge about the factors influencing professional development choices. The research question was To what extent are middle-level teachers' professional development choices associated with selected factors? The factors investigated were as follows: (1) a greater than 50% assigned time curriculum director with responsibilities for coordination of professional development, (2) meeting criteria for designation as a middle school and (3) the availability of and participation in professional development activities at the school level, the district level, and the higher education level. No significant differences at the 0.05 level were found between the selected factors: (1) the presence or absence of a greater than 50% assigned time curriculum director and (2) designation of the site as a middle school. However, the findings indicated there was a significant difference between school, district and higher education levels in participation, F(2,151)=5.94; p=0.003. Teachers' participation in higher education level professional development activities/program was lower than participation in professional development activities at the school and district level.