This paper demonstrates that the phonetic vowel sequences of Konni can be analyzed as a dipthongization of long mid vowels. Evidence from phonetics, phonological rules, and tone is cited to support this conclusion. The vowel harmony system of Konni is reviewed and underspecification of features is seen to play a crucial role in explaining vowel harmony. Vowel harmony and underspecification are combined with the coindexing concept of Bruce Hayes to account for dipthongization in Konni. (Author/MDM)