In a comparison of the melodies in the speech of Mandarin Chinese and Caucasian American mothers, striking similarities were found: (1) in the overall distribution and average structure of melodic contours; (2) in close contextual links to given forms of intuitive parental care; and (3) in a tendency to neglect lexical tones in favor of pitch modulation. These findings strongly support the notion of a cross-cultural universality of maternal melodies, and indicate a primary biological determination. At the same time, significant differences were found with regard to the extent of speech adjustments. Chinese mothers raised their overall pitch less and expanded pitch excursions less than did American mothers. This finding reflects certain constraints on pitch modulation which may be explained linguistically and culturally. Chinese mothers compensated for such constraints through a high proportion of unconstrained modeling sounds. (PCB)