This study investigated children's tonal awareness by measuring their abilities to detect dissonance in major tonality using the author-created "Tonal Dissonance Detection Test." A two-way analysis of variance of 312 elementary school subjects' Tonal Dissonance Detection Test scores revealed that first- and second-graders' dissonance detection abilities were significantly weaker than those of their third- to sixth-grade counterparts. Subsequent analysis revealed neither a significant gender effect nor interaction between grade level and gender. Findings are consistent with related study of the perception of tonality and tonal expectancies in children and adults. Given the homogeneity of the sample, the longevity of the music instructor, the school's sequential Kodaly-based curriculum, and conclusions of prior research, discussion considered the impact of musical instruction and musical development on the ability to perceive tonality. The author suggested the two aforementioned constructs might be studied by comparing the same perceptual skills of children from both Western and non-Western cultures. (Contains 2 tables and 2 figures.)