This descriptive study compares the entry-level pedagogical content knowledge of single subject mathematics credential candidates based on career status and undergraduate majors. Career changers from science, technology, engineering or math (STEM) fields are compared to first career candidates to see if they bring different skills and knowledge to the teaching of mathematics. This study also factors in the candidates' undergraduate majors--mathematics, STEM (non-math) majors, and other non-STEM majors--with the goal of uncovering any differences in the candidates' specialized knowledge for teaching mathematics. Using mixed methods--a qualitative written survey (N = 69) of the participants' educational and occupational background, a quantitative measure of pedagogical content knowledge (PCK), and in-depth interviews (N = 16)--the volunteer participants' common content knowledge (CCK) and specialized knowledge for teaching mathematics (SCK) were compared to see if preservice teachers had (1) differing perceptions in regard to decisions to teach and in regard to the qualities, knowledge and skills needed to effectively teach secondary mathematics; and (2) differing types of pedagogical content knowledge based on career status or undergraduate major. Rather than sharply distinguish PCK among different demographics, however, the data indicated more about how individuals, rather than groups of candidates, understand mathematical content, how they communicate the mathematics, and how they make instructional decisions at the beginning of their single subject mathematics credential program. The prospective teachers evidenced strengths and gaps in their CCK and SCK, but it does not appear to be defined by their career status or undergraduate major. The implications for credential candidates and Teacher Education Programs is that most candidates need to develop multiple representations for math concepts, make connections between mathematical concepts and procedures and link mathematical models with contextual situations thus building the specialized knowledge for teaching mathematics. [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.]