This chapter draws on an analysis of two sequences of five videotaped lessons taught by two case study teachers, one Flemish and one Hungarian, both of whom were defined locally as effective. The lesson sequences, both on linear equations, show how teachers’ didactic decision making is informed by three different curricula: an intended curriculum, an idealised curriculum and a received curriculum. An intended curriculum, as defined by the second international mathematics study (SIMS), draws on systemic expectations with regard to mathematics teaching and learning. The idealised curriculum reflects individual teachers’ personal but articulable beliefs about and goals for mathematics, its teaching and learning. The received curriculum reflects those beliefs and goals consequential of hidden and inarticulable cultural influences. The data indicate that where the three curricula converge, students are more likely to experience coherent learning experiences in relation to systemic goals than when they diverge.