In this digital era, a fundamental challenge is to design digital reading materials in such a way that they improve children's reading skills. Since reading books is challenging for many fifth graders--particularly for those genetically susceptible to attention problems--the researchers hypothesized that guidance from a digital Pedagogical Agent (PA) could improve students' reading motivation and incidental vocabulary learning. Using a sample of 147 fifth-grade students, the researchers carried out a randomized control trial with three groups of students reading: (a) hardcopy (print) books, (b) digital books, and (c) digital books with a PA. For students with a genetic predisposition to attention problems, carriers of the DRD4 seven-repeat allele, the PA supported their incidental vocabulary learning. For noncarriers, there were no effects of the digital reading materials or the PA.