While it is widely accepted that teacher quality is one of the most influential factors in predicting positive student outcomes such as academic success, identifying the key attributes and indicators of a quality teacher has been challenging. Due to mounting evidence that a teacher's pedagogical content knowledge (PCK) impacts both their practices and their students' learning outcomes, it is widely accepted that teaching quality should be evaluated in terms of PCK. Teacher performance assessments, such as the edTPA, provide preservice teachers an opportunity to rigorously reflect on their instructional practices, make connections to research and theory, and therefore, theoretically have the potential to positively influence PCK development. The purpose of this longitudinal qualitative study was to investigate the characteristics of preservice science teachers' (PST) PCK development during the last year of a teacher preparation program, including student teaching and the edTPA creation process. This investigation of PCK development focused on the integration of components of PCK (e.g., knowledge of student understanding [KSU], knowledge of instructional strategies and representations, knowledge of assessment, knowledge of curriculum, and orientations to teaching science). This study also sought to explore the potential influence of the edTPA creation process on preservice science teachers' PCK development, a current blind spot in the literature. Both the Refined Consensus Model (Carlson et al., 2019) and the Pentagon model of PCK (Park & Oliver, 2008a) served as the conceptual frameworks of this study. Participants of the study were six undergraduate science education majors in an undergraduate science education program. Data sources included observations, interviews, the researcher's field notes, edTPA portfolio materials, lesson plans, surveys, and other artifacts and documents, such as assignments and written reflections from their science education methods courses. Data were analyzed using three approaches: (1) coding with a priori codes, (2) the PCK Map approach, which includes the in-depth analysis of explicit PCK followed by an enumerative approach to create PCK Maps, and (3) the constant comparative method. The results revealed that, in general, the PSTs' PCK was weak and fragmented. While no consistent pattern of PCK development was discernible through analyzing participant's PCK Maps, further analysis revealed five emerging themes regarding common characteristics of preservice science teachers' PCK and PCK development over the course of their final year of teacher preparation: (1) PSTs' orientations to teaching science remained relatively stable and rarely influenced their PCK or instructional practice; (2) PSTs' KSU was limited but developed through teaching experience, in association with their knowledge of assessment; (3) some aspects of PSTs' KSU developed through the integration of their knowledge of science curriculum; (4) the relationship between KSU and knowledge of instructional strategies and representations was central to PSTs' PCK; and finally, (5) despite being frequently integrated into their PCK, PSTs' understanding of assessment methods and the purposes of assessment were limited. Data analysis also revealed five aspects of how the edTPA portfolio creation process influenced preservice science teachers' instructional practices and PCK development. The edTPA portfolio creation process facilitated PSTs to: (1) increase reflection on their teaching practice; (2) increase integration between components of their PCK; (3) expand their KSU and more frequently integrate it into their PCK; (4) more frequently implement student-centered instruction; and finally, (5) develop and more frequently integrate their knowledge of assessment into their PCK. Discussion centers around how this research contributes the growing body of scholarship surrounding the characteristics of PCK and PCK development among PSTs and becomes the first empirical study to investigate the impact of the edTPA on PSTs' PCK development. Finally, the implications of this study for future research, teacher preparation programs, and educational policy are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]