Students enrolled in a university educational psychology course were subjects in this study to determine the effects of preparation on the level of vagueness in lecturing. Subjects were provided either five or eleven minutes to prepare lecture notes on a given topic. Results showed preparation time, number of note words, and a test of topic knowledge all yielded highly significant correlations with vagueness. The lecturer's perception of his own effectiveness had a weak relationship with vagueness but a significant relationship with verbal productivity. Females were found to be more predictable then males. (Author/HOD)