With the application of the Contrastive Hierarchy Theory, the contrastive features of preliterary Scandinavian vowels are here inferred from the interaction between targets and triggers for metaphonic fronting, rounding and breaking. One Proto-Scandinavian feature hierarchy is reconstructed for prominent syllables and another for non-prominent ones. The former hierarchy sustained contrasts that differed from the latter, including contrast for rounding and a preserved distinction between Pre-Germanic */i/ and */e/. A prominence system is reconstructed that predicts both the outcome of syncope and the distribution of the two vowel systems between syllables. The analysis neatly accounts for many notorious cruxes of umlaut and breaking that correlate with the prosodic position of the trigger, including the frequent absence of i-umlaut in light syllables.