Czech is described as having word stress fixed on the first syllable, independent of vowel quantity. The pitch peak of a word generally falls on that first, stressed syllable. However, in some environments, the pitch peak shifts to a later syllable, leading to the perception that this later syllable is more prominent. This study investigated the phonetic factors conditioning such divergent placement of stress and pitch peak in Czech. Native speakers produced contextually embedded trisyllabic nonsense words with high-pitch accents. Vowel height and quantity in the first and second syllable were independently varied to assess their effect on syllable pitch and the timing of the pitch peak. Whether a syllable was stressed constituted the third independent variable in the analysis. To determine whether stress remained on the first syllable, the timing of stress-related properties, i.e., amplitude and syllable lengthening, was examined. Results showed that a high vowel in either syllable tended to raise the pitch, but the second vowel could only attract the pitch peak if the first vowel was short and low. A long first vowel prevented accent shift to the second syllable. Stress-related properties remained largely confined to the first syllable, although the amplitude maximum occasionally shifted to the second syllable, if long.