This mixed-methods study investigated the relationships among preservice teachers' efficacy beliefs, pedagogical content knowledge (PCK) and their domain knowledge (DK) as related to mathematics and science teaching. Quantitative results revealed that participants' PCK was significantly correlated with their mathematics and science efficacy beliefs. Additionally, participants' mathematics and science DK did not predict their mathematics and science personal efficacy beliefs, however, their PCK score predicted participants' outcome expectancies. Interview analysis revealed five inter-related key themes, labeled as: "Previous academic experiences," "Mathematics and science PCK beliefs," "Personal efficacy," "Outcome expectancies" and "Emotions." These common themes describe participants' views of their quality teacher training and thinking about planned instruction. Educational implications are discussed in relationship with study findings.