The Nez Perce language, a highly endangered American Indigenous language, has been of great interest in phonology over the years due to its unusual vowel system and vowel harmony process. It has five monophthongs and seven diphthongs, all with phonemic length. This system is unusual because rather than /i, e, a, o, u/ as is common, the Nez Perce inventory is /i, ae, a, o, u/. This uncommon inventory leads to two seemingly unrelated dominant, /i, a, o/, and recessive, /i, ae, u/, vowel harmony groups. To date there has been no phonetic analysis of the vowel system. This paper provides an acoustic analysis of the vowels as well as the vowel harmony system. Five native speakers (two male and three female) were used to analyze the vowels and the three female native speakers were used for the vowel harmony study. Results support the current vowel system analysis for Nez Perce. The vowel harmony data lends support to the current advanced tongue root analysis; however it also poses questions for future research.