Poor executive functioning has been implicated in children’s concurrent and future behavioral difficulties, making work aimed at understanding processes related to the development of early executive function (EF) critical for models of developmental psychopathology. Deficits in EF have been associated with adverse prenatal experiences, genetic influences, and temperament characteristics. However, research has had limited ability to disentangle their effects due to limitations inherent to biological parent-child research designs. The present study examined EF and language development in a sample of 361 toddlers who were adopted at birth and reared in non-relative adoptive families. Predictors included genetic and prenatal influences as inherited from birth mothers, and child negative emotionality. Structural equation modeling indicated that the effects of prenatal risk on toddler effortful attention at age 27 months became nonsignificant once genetic influences were considered in the models. In addition, genetic influences had unique effects on toddler effortful attention and language development. Latent growth modeling indicated that increases in toddler negative emotionality from 9 to 27 months were associated with poorer delay of gratification and poorer language development. Mechanisms of intergenerational transmission of EF deficits are discussed.