Prior research has shown that vocabulary instruction can enhance the comprehension of passages when instruction includes definitional and contextual information, provides multiple instructional encounters with the words, and requires learners to engage actively in processing of word meanings (M. F. Graves, 1986; S. A. Stahl & M. M. Fairbanks, 1986). However, measures have not been reported to estimate the relative intensity of vocabulary interventions that promote comprehension. The procedure of S. F. Warren, M. E. Fey, and P. J. Yoder (2007) designed to document the intensity in communication and language development intervention research was applied to 3 classic vocabulary instructional studies. Although the procedure could not be applied directly to the studies, 2 statistics similar to those generated by the procedure of S. F. Warren et al. could be gleaned from the research reports: the Average Minutes of Instruction per Word (MI) and the Average Exposure-Minutes of Instruction per Word (E-MI), which accounts for the total instructional time, the number of words taught, and the exposures per word. Application of the analysis to the 3 studies revealed that there were threshold intensity values for ME and E-MI for vocabulary interventions to affect comprehension. Difficulties in applying the framework of Warren et al. to vocabulary instruction research are addressed.