Perceived influences of biology and English department heads were investigated using a discriminant analysis test of Biglan's model. Attention was directed to the influence of discipline versus the structural variables of department size, type of institution, and highest degree awarded. Questionnaires completed by 586 heads of biology and English departments provided estimates of the level of their influence in 19 functional areas commonly associated with chairing academic departments. It was found that discipline is of secondary importance in explaining the variance in responses of department chairpersons to questions dealing with perceived influence. In both English and biology departments, the mean influence value for chairpersons in small departments was less than that of those of medium size, which was in turn less than that of those in large departments. There was a significant increase in both disciplines in the mean perceived influence value with each successively higher degree awarded. Using stepwise discriminant function analyses, discipline in combination with highest degree and department size accounted for more of the variance than did discipline. The findings are presented in 3-dimensional graphics by plotting the group centroids against the discriminant functions. (SW)