Measuring the quality of classroom-based interactive shared book reading within the early childhood classroom represents a specific dimension of teacher-child interactions that is of great interest to researchers. This interest reflects decades of research demonstrating the benefit of reading to young children in both the home and the classroom. The purpose of this validation study was to conduct a systematic investigation of the psychometric characteristics of a revised version of the Systematic Assessment of Book Reading (SABR-2.2), a measure that examines qualities of teacher talk through observation of classroom shared book reading. Validation of the SABR involved video-based coding of book-reading sessions in pre-k and Kindergarten classrooms (n = 286 teachers and 877 children). Teacher race/ethnicities included: Caucasian (64%), African American (27%), Latino (19%), American Indian/Alaska Native (1%), Asian (4%), and 4% reported their ethnicity as 'other'. Children's race/ethnicity was Caucasian (52.3%), African American (39.7%), Latino (30.6%), American Indian/Alaska Native (1.2%), Asian (5.3%), and 1.5% reported their ethnicity as 'other'. Using the SABR, we coded the frequency of 11 teacher behaviors that relied on explicitly defined behaviors and sets of keywords that indicated the presence of a behavior. Factor analyses yielded a single factor with item loadings between 0.41 and 0.86. Inter-rater reliability estimates were high (i.e., 95%-99%). Test-retest reliability revealed that the SABR factor scores were strongly correlated (r = 0.71) at Fall and Spring. We established concurrent validity with moderate relations with the ELLCO (rs = 0.31-0.50). Predictive validity of the SABR was investigated for 877 children tested at base-line and follow-up. Findings revealed a significant and small association between teachers' SABR scores and gains in children's vocabulary and print knowledge scores. Additional analyses were conducted to examine psychometrics by race/ethnicity.