Low cost, non-invasive instruments for the identification of high academic potential in early childhood education and care are scarce, and the complexity of cognitive development indicates that combinations of screening instruments are needed. This study investigates the reliability and validity of three instruments (individually and in combination) in a longitudinal study of 136 Norwegian children in kindergarten through 8th grade with the research questions: (1) Do children's scores on screening instruments accurately identify high academic potential in kindergarten? (2) Are children's scores on kindergarten screening instruments consistent with high academic achievement in 8th grade? (3) Is early screening for high academic potential biased by the child's gender, family income, birth semester, or level of the mother's education? A mean score combination of the instruments provided the most reliable and valid screening, but as systematic error by gender and level of mother's education was identified, similar instruments should be used cautiously.