The present study investigated the development of n = 129 early childhood teachers' mathematics content knowledge, mathematics pedagogical content knowledge, mathematics anxiety, and enjoyment of mathematics over 4 years from teacher training to practice. Latent autoregressive models with cross-lagged effects were applied. Scalar measurement invariance of the model also allowed analyses of intraindividual change of knowledge and emotions. Results indicate a decline of mathematics anxiety, an increase of enjoyment and mathematics content knowledge and mathematics pedagogical content knowledge, and medium (emotions) to strong (knowledge) autoregressive but limited cross-lagged effects. No cross-lagged effects between emotions and knowledge over time were found. All but one of the correlations at training disappeared during transition to practice. Theoretically assumed differences between early childhood teachers' knowledge and emotions in teacher training and practice are discussed in light of the results. The transition seems to be more challenging on an emotional level than on a cognitive level. Implications for early childhood teachers' training are given--for example, that pleasant emotional experiences have to be made visible during training.