Song sparrow (Melospiza melodia) songs are composed largely of pure-tonal sounds. This paper investigates the role that learning plays in the development of the tonal structure of song sparrow songs, as well as the role that tonal quality plays in determining the suitability of songs as models for learning. 20 birds were trained with both normal pure-tonal songs and modified songs that included harmonic overtones. The harmonic-modified songs were obtained from birds singing in a helium atmosphere, the result of which is to perturb vocal tract resonances and thus alter a song's tonal quality. Subjects learned equally well from normal and harmonic models. Birds that learned material from harmonic models reproduced some of this material with harmonic overtones, but the majority of notes learned from harmonic models were subsequently reproduced as pure-tonal copies. Thus, the tonal structure of songs does not influence young song sparrows in their selection of song models, but there is a strong tendency to reproduce songs in a pure-tonal fashion, even if learned from harmonic models.