A computerized test of preparedness for effortful processing (alerting attention), response to orienting cues (orienting attention), and response to the interference of competing demands (executive attention) was administered to a diverse sample of 249 children (47% female, 4.96 to 7.27 years) to assess developmental properties and sociodemographic correlates of task performance. Older children and socially advantaged children demonstrated greater proficiency in overall accuracy and speed of responding. Boys and socially advantaged children improved more in response to alerting cues. Older children improved more in response to orienting cues. Older children, socially advantaged children, African American, and Hispanic children resisted the interference of competing demands better. Findings are discussed in the context of developmental and sociodemographic factors relevant to attention and executive functions.