With our analyses of the ECLS-B data set, we considered three covariates—age at initial assessment, poverty, and race/ethnicity—to control for potential influences. Within the ECLS-B 9-month data collection, the age at which infants were assessed ranged from 6 months to 22 months, with 72% at 8 to 10 months of age (Flanagan & West, 2004). Hence, we statistically controlled for age at the time of assessment for age-sensitive variables. Similarly, we statistically controlled for poverty and employed the federal poverty guideline as our definition. Finally, with respect to race/ethnicity, we statistically controlled for the five race/ethnic groups delineated in Table 1.