This study investigated the effect of encouragement, inspection, and training on the effectiveness of supervisors' developmental activities with their subordinates. Treatment groups were established on each variable. A specially developed questionnaire was administered, before introduction of the study variables and again six months afterward, to subordinates who reported on the developmental activities of their supervisors. Multiple-range Tests and Students "t" Tests were used to assess the significance of changes following introduction of the study variables. Students "t" Tests showed no significant differences directly attributable to the variables. The lowest one-third ranking supervisors in each treatment group were comparable to a "national average" level of supervisors; and changes in the mean scores of these groups also proved insignificant. When an analysis was made of scores by the lowest ranking third of the supervisors on ten recommended activities, only five of the 30 comparisons among treatment groups showed significant changes. Thus, the significance of the variables, particularly encouragement and training combined, was not substantiated. Several recommendations were made for improving future studies of this type. (The document includes 11 tables, 12 appendixes, and numerous references.) (author/ly)