The purposes of this study were to: develop and measure the effectiveness of instructional units designed to enable young adult farmers to improve their ability to use farm management principles when making decisions, and measure the influence that independent variables have on the young farmer's level of understanding these principles. McCormick's testing instrument for measuring "Seven Profit-Maximizing Principles" was revised slightly to measure the understanding of farm management principles by the farmers who were placed in experimental and control groups. Questionnaires were also prepared to determine the young adult farmer and teacher reaction to the instructional units. The prepared units, when used by teachers with inservice training on their use, were significantly more effective than traditional techniques of teaching farm management as measured by the post-test scores. Teachers who used the units without inservice training ranked second in effectiveness out of three instructional approaches but were not significantly better than those who used traditional techniques. Students with the most formal education and managerial responsibility and best attendance at farm management meetings had a better understanding of farm management principles; older, married, and more experienced students scored higher on exams. (Author/NL)