In Estonian, as in a number of other languages, the nuclear pitch accent is often low and level. This paper presents two studies of this phenomenon. The first, a phonetic analysis of carefully structured read sentences shows that low accentuation can also spread to the prenuclear accents in an intonational phrase. The resulting sentence contours are used as evidence to evaluate alternative phonological analyses of low accentuation, and H+L* is shown to account best for the data. The second study presents quantitative evidence from fundamental frequency values which supports this phonological analysis. Finally, the distribution of prenuclear pitch accents is discussed. High and low accents can co-occur in an intonational phrase, but only in patterns obeying a specific sequential constraint. A fragment of an intonational grammar for Estonian is presented capturing the observed distributional restrictions. (Contains 13 figures and 6 footnotes.)