There are multivariate influences on the development of children's executive function throughout the lifespan and substantial individual differences can be seen as early as when children are 1 and 2 years of age. These individual differences are moderately stable throughout early childhood, but more research is needed to better understand their origins. To some degree, individual differences in executive function are correlated between mother and child, but no research to date has examined these associations prior to when children are preschool age, nor have any studies considered the role of fathers' and mothers' executive function in tandem. Here, we use a sample of 484 families (Mothers 89.2% white; Fathers 92.5% white) in three countries (UK, USA, Netherlands) to investigate the role of each parents' executive function on the development of children's (49.7% female) executive function from 14 (M = 14.42, SD = 0.57) to 24 (M = 24.47, SD = 0.78) months, as well as parenting practices that underlie these associations. Results of structural equation models suggest stability in some-but not all-components of executive function and growing unity between components as children age. We replicate extant findings such that mothers' executive function predicts children's executive function over and above stability and extend these findings to include associations between father and child skills. We find an additive role of fathers' EF, similar in magnitude to the role of mothers' EF. Finally, for both mothers and fathers we find that sensitivity and autonomy supportive practices mediate the relations between parents' and children's executive function.