The present study investigates the validity of a 4-point rating scale used to measure the level of preschool children's orientation to literacy during shared book reading. Validity was explored by (a) comparing the children's level of literacy orientation as measured with the "Children's Orientation to Book Reading Rating Scale" (COB) with a teacher's rating of a child's level of attention and effortful control on the "Children's Behaviour Questionnaire" (CBQ), and (b) computing the predictive validity of a child's COB rating with overall levels of emergent literacy at the end of the preschool school year. This study involved 46 preschool children from low-income backgrounds; children's literacy orientation was rated during a group teacher-led book reading. Children's ratings of literacy orientation during shared book reading using the global 4-point COB scale were significantly correlated with teacher ratings of a child's attention and effortful control as measured on the CBQ. Hierarchical regression results indicated children's literacy orientation significantly predicted children's end-of-year alphabet knowledge and overall emergent reading skills above and beyond the variance contributed by children's language skills and family income. The validity of a global rating for indexing children's level of literacy orientation was supported. Educational implications and recommendations for the COB as a component of early literacy assessment are discussed.