A study investigated the efficacy of the mnemonic graphic organizer strategy on the vocabulary acquisition of beginning and advanced adult English-as-a-Second-Language (ESL) students. Subjects, 48 adults enrolled in two adult ESL classes at a metropolitan adult school, were randomly divided into control and experimental groups. The experimental treatment was conducted in three 45-minute sessions over a period of 1 week. Subjects in the control and experimental groups received the same instruction in the topic material, but subjects in the experimental group used a mnemonic graphic organizer strategy for vocabulary acquisition. Results indicated that the use of graphic organizers across high and low ability groups was as effective in subjects' vocabulary acquisition as the regular classroom technique, and was significantly effective with beginning ESL students over and above the regular classroom instruction. Findings suggest further support for the utilization of the cloze technique for ESL proficiency testing. (Six tables of data are included; 6 appendixes containing a description of the steps in constructing and using graphic organizers, the student consent form, pre- and post-test vocabulary lists for both classes, instructional material on how to use reference material, the graphic organizer used in the study, data from the study, and 92 references are attached.) (RS)