The aim is to investigate early childhood mathematics in a preschool unit in Sweden. A mixed-method research approach and a case study research design were used. Three preschool staff members and 19 children were enrolled. Data were collected by means of observations and a focus group interview. Numerical and thematic analyses were conducted. The mean value of ratings of early childhood mathematics in the preschool unit approached 'good' (m = 4.5) and can be described by means of six themes: one to ten mathematics; a short question and a short answer; embedded mathematical concepts in everyday routines and play activities; whole-group mathematical circle times incorporating support for younger children and those who are struggling; accessible robots, materials and tools, and small group mathematics. The study could form a basis for discussions on such matters as early childhood mathematics and differentiation in preschools, both in Sweden and in other countries.