The purpose was to evaluate ways of predicting the onset frequency of the second vowel formant (F2) following consonant constrictions. Spectrograms of 604 constrictions were measured to obtain the frequency and slope of F2 offset just prior to each constriction, the duration of the constriction, and the frequency of F2 onset after the constriction. Three types of F2 onset prediction were applied to each constriction: (1) holding the F2 offset frequency, (2) linear extrapolation of F2 offset slope, and (3) exponential extrapolation of the offset slope. Statistical analyses of these data indicated that linear extrapolation gave poor results, that holding predictions were superior to predicting merely the modal onset, and that exponential extrapolations were better than holding offsets under certain conditions of offset slope and frequency region. Articulatory place and complexity of consonant constriction were found to be related to prediction error.