An adult educator in Butler, Pennsylvania, noticed that, although students who took the General Aptitude Test Battery (GATB) seemed highly motivated to improve their basic skills in mathematics and spatial relations, only 2 of her 20 students who took the GATB made a concerted effort to develop their vocabulary. Thinking that those two students were a peer vocabulary-building team because they were brothers, the instructor undertook an action research project to increase students' vocabulary skills by using a peer vocabulary-building team system. During the 4-month study, the instructor had students spend 15 30-minute study sessions with a peer vocabulary team. Data were collected in three ways: field observations, interviews with team members, and pre- and posttests to measure vocabulary gains. Of the 16 students enrolled in the instructor's GATB preparation class, 12 participated in the peer vocabulary-building team system. After 4 months, all 12 students demonstrated word recognition gains ranging from 23% to 583%. (Attachments constituting approximately 60% of this document contain a chart detailing the 9 aptitudes measured by 12 tests in the GATB and a student vocabulary progress record.) (MN)