The transition into school occurs at the intersection of multiple environmental settings. This study applied growth curve modeling to a sample of 1,364 American children, followed from birth through age 6, who had been categorized by their exposure to cognitive stimulation at home and in preschool child care and 1st-grade classrooms. Of special interest was the unique and combined contribution to early learning of these 3 settings. Net of socioeconomic selection into different settings, children had higher math achievement when they were consistently stimulated in all 3, and they had higher reading achievement when consistently stimulated at home and in child care. The observed benefits of consistent environmental stimulation tended to be more pronounced for low-income children.