In this quantitative research study the researcher investigated the effect of vocabulary instruction on the reading achievement of at risk students. A quasi-experimental design was used to determine the effect that vocabulary instruction had on the reading achievement of the at risk students. The sample used in the study was purposive, because they were selected based on some characteristics that they shared. The Georgia Criterion Referenced Competency Test (CRCT) was used as the pre and posttest. The 101 participants was administered The Criterion Referenced Competency Test (CRCT) as a pre-test in second grade and as a posttest in third grade. Participants in the experimental group were instructed using Vocabulary Works, a vocabulary program authored by Dr. Alvin Granowsky. However, participants in the control group did not receive any vocabulary instruction at all. After conducting the study it was found that there was no significant difference in the reading achievement of students who received daily vocabulary instructions and students who did not. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]