Phonological processes are often sensitive to morphological, prosodic, and derivational structure. In terms of derivational structure, a common factor are strata or levels, as in Lexical Phonology (Kiparsky 1982) or Stratal OT (Bermúdez-Otero 2018). Two commonly argued strata are the stem-level and word-level cophonologies which are morphologically triggered. In this paper, I argue that Armenian has cyclic processes which follow this stratal model. However, I also show that Armenian phonology utilizes a prosodically-triggered cophonology. This cophonology is triggered by the prosodic misalignment between the morphological stem (MStem) and syllable boundaries. This occurs before vowel-initial inflection. I argue that this misaligned MStem is parsed into a sublexical prosodic constituent, the Prosodic Stem (PStem: Downing 1999a). This PStem-level cophonology applies between the stemlevel and word-level cophonologies.