To determine the effect of field trips on student achievement in each of four subject matter areas in vocational agriculture, 12 schools offering approved programs were randomly selected and divided into a treatment group and a control group. Uniform teaching outlines and reference materials were provided to each group. While no field trips were taken in the control groups, four field trips were used in the treatment schools in teaching each of the four units of animal health, commercial fertilizers, small gasoline engines, and farm credit. A pretest versus posttest, control versus treatment group experimental design was used in this study. The control schools achieved significantly higher than field trip schools in the farm credit unit when academic ability factors were used as covariates. A highly significant difference in favor of the field trip schools was obtained for the commercial fertilizers unit when abstract aptitude, crop acres, department size, and teacher tenure were used as covariates. No other significant results were noted. This Ph.D. dissertation was submitted to Iowa State University. (GB)