When and how does one learn to associate emotion with music? This study attempted to address this issue by examining whether preschool children use tempo as a cue in determining whether a song is happy or sad. Instrumental versions of children's songs were played at different tempos to adults and children ages 3 to 5 years. Familiar and unfamiliar songs were used to examine whether familiarity affected children's identification of emotion in music. The results indicated that adults, 4 year olds and 5 year olds rated fast songs as significantly happier than slow songs. However, 3 year olds failed to rate fast songs differently than slow songs at above-chance levels. Familiarity did not significantly affect children's identification of happiness and sadness in music.