The study presented in this article investigates how the curriculum is implemented and transformed by teachers in mixed-age and age-homogeneous groups, the most common age-constellations in the Swedish preschool. The data was collected through groups interviews with preschool teachers. The interviews were transcribed and analysed with the support of thematic analysis and connected to a sociocultural perspective on learning. The findings show that the teachers in the different age formations use both the same and different teaching strategies, which means that the curriculum is implemented and transformed in different ways. The teaching and learning events in the age-homogenous groups appear to be more structured and planned, whereas in the mixed-aged groups the teaching is more spontaneous and embedded in the everyday activities.