A study was designed to compare the high front /i/ and high back /u/ vowel in children at risk and not at risk to stutter. Recordings were made of children playing with parents for 10 minutes between 15 and 36 months of age. Anatomical and linguistic influences did not differ across subjects with the exception of the 24 month period. At risk children were slightly taller at 24 months. Spontaneous utterances from each child were digitized into a CSL, Model 4300. The F1 and F2 of the steady-state portion of each /i/ and /u/ vowel was measured. Not-at-risk children demonstrated values typical of normally- developing children. Repeated measure ANOVAs showed that children who were at risk to stutter had significantly higher formant values for F1 for both /i/ and /u/ vowels. These results suggest that the tongue height is lower than it should be for the high vowels. Formant frequencies for F2 for both /i/ and /u/ were significantly higher also reflecting a more forward tongue position for the front and the back vowels in at-risk children.