We study differences in the time parents spend with boys and girls at preschool ages in Canada, the UK and the US. We refine previous evidence that fathers commit more time to boys, showing this greater commitment emerges with age and is not present for very young children. We next examine differences in specific parental teaching activities such as reading and the use of number and letters. We find the parents commit more of this time to girls, starting at ages as young as 9 months. We explore possible explanations of this greater commitment to girls including explicit parental preference and boy-girl differences in costs of these time inputs. finally, we offer evidence that these differences in time inputs are important: in each country the boy-girl difference in inputs can account for a non-trivial proportion of the boy-girl difference in preschool reading and math scores.