This article uses longitudinal data from four Mexican-American children to explore two aspects of the acquisition of Spanish word stress that precede and accompany learning of the stress system itself. First, contrary to Allen & Hawkins' proposed universal ‘trochaic bias’ (Allen 1982, Allen & Hawkins 1977, 1979, 1980), it is shown that children have a ‘neutral start’ in stress learning: they approach the task of stress learning unbiased towards any particular stress type. Secondly, several examples are found in which children's attention to phonetic or semantic aspects of normatively unstressed syllables leads them to shift stress to that syllable.