Questions concerning the developmental timetable for the acquisition of musical knowledge have been studied very little. This study of infants suggests a precocious onset of musical scale knowledge, an important aspect of music cognition, as findings indicate that infants better perceived mistunings in native than in nonnative scales. Six‐ and 12‐month‐olds were tested in noticing increases in the frequency of a randomly selected note in a melody based on the Western major scale (most common Western scale based on the semitone), the Western augmented scale (infrequently used Western scale but also based on the semitone), and the Javanese pelog scale (nonnative scale not based on the semitone). An operant head‐turn procedure was used in which the well‐tuned version of each melody was played repeatedly through a loudspeaker, and the infants learned to turn their heads toward the speaker in anticipation of a visual reinforcer when they noticed a frequency change in one of the melody notes. The 12‐month‐olds' performance was better on the major scale than on either the augmented or pelog scales. In contrast, the 6‐month‐olds' performance was better on both the major and augmented scales than on the pelog scale, and their performance was similar on the major and augmented scales. These findings suggest that substantial musical acculturation occurs as early as 6 months of age and that infants may proceed from acquisition of knowledge of the semitone as a basic structure of Western music to acquisition of more specific knowledge of the major scale by 12 months of age.