Russian maintains a contrast between non-palatalized and palatalized trills that has been lost in most Slavic languages. This research investigates the phonetic expression of this contrast in an attempt to understand how the contrast is maintained. One hypothesis is that the contrast is stabilized through resistance to coarticulation between the trill and surrounding vowels and prosodic positional weakening effects-factors expected to weaken the contrast. In order to test this hypothesis, we investigate intrasegmental and intersegmental coarticulation and the effect of domain boundaries on Russian trills. Since trills are highly demanding articulatorily and aerodynamically, and since Russian trills are in contrast, there is an expectation that they will be highly resistant to coarticulation and to prosodic influence. This study shows, however, that phonetic variability due to domain boundaries and coarticulation is systematically present in Russian trills. Implications of the relation between prosodic position and lingual coarticulation for the Degree of Articulatory Constraint (DAC) model, Articulatory Phonology, and the literature on prosodic strength are discussed. Based on the quantitative analysis of phonetic variability in Russian trills, we conjecture a hypothesis on why the contrast in trills is maintained in Russian, but lost in other Slavic languages. Specifically, phonological strategies used by several Slavic languages to deal with the instability of Proto-Slavic palatalized trills are present phonetically in Russian. These phonetic tendencies structure the variability of Russian trills, and could be the source of contrast stabilization.