Previous researchers have concluded that there is a need for determining how vocabulary instruction effects vocabulary comprehension and reading comprehension for young learners. Researchers have implemented morphemic strategies in various studies to identify effective methods for vocabulary instruction. In the present study, four prefixes were taught to students with disabilities to extend vocabulary research by using a morphological approach with a focus on prefix instruction. In addition students were taught how to combine the meaning of a prefix to the meaning of a root word. Data patterns indicate an increase in students' ability to provide definitions for prefixed words while the transfer to reading comprehension was minimal. The results of this study provide direction for future research in implementing a morphemic approach for vocabulary instruction.