First findings of IEA’s “Teacher Education and Development Study in Mathematics (TEDS-M)” had revealed differences in the demographic background, prior knowledge, opportunities to learn (OTL), and outcomes of primary teacher education between future teachers from different countries. In this chapter, two hypotheses are examined: (1) OTL and teacher background are significant predictors of mathematics content knowledge (MCK) and mathematics pedagogical content knowledge (MPCK) as teacher education outcomes. (2) OTL effects are partly mediated by differential student teacher intake. Data from multilevel models reveal that effects on MCK are in general larger than on MPCK. Gender, prior knowledge and OTL in mathematics are significantly related to both types of outcomes whereas other background characteristics affect MPCK only. Motivation mediates the effects of prior knowledge and the OTL effects are partly mediated by teacher intake. Consequences for educational policy are discussed based on these results. Policymakers have on the one hand to be aware of the continuing problem of societal inequalities. Providing OTL in mathematics as well as increasing entrance selectivity may, on the other hand, have positive consequences for the outcomes of primary teacher education.