ATR, advanced tongue root, is a phonological feature among vowels. As vowels assimilate to share the same value of that feature, they display ATR harmony. This is a common phenomenon among many African languages. ATR harmony is examined in this paper as manifested across morpheme boundaries wihin nouns in a Surmic language of Ethiopia called Bale. The data presented was collected at a workshop on ATR harmony held by SIL International in Mizan Teferi, Ethiopia, 2009. The vowel system in Bale displays a nine vowel inventory with a feature dominance of [+ATR] vowels which spread their feature both leftward and rightward to recessive [–ATR] vowels. The [+ATR] dominance is also present as a floating feature without any phonological material. The vowel /a/ is analysed as a neutral vowel, co-occuring with both [+ATR] and [–ATR] vowels within roots.