The purpose of this study was to determine if leadership training, given to informal leaders, had a positive effect on manufacturing productivity. The leadership attributes of informal leaders were assessed using the Leader Attributes Inventory (LAI). Furthermore, the performance of informal leaders was measured using the Leader Effectiveness Index (LEI). Non-management employees from various departments in a manufacturing facility were placed in one of four experimental groups. A Solomon four-group experimental design was employed. A one-group pretest-posttest design was used to control threats to internal validity. The one-way analysis of variance procedure (ANOVA) was used to determine if there were statistically significant increases in manufacturing productivity of informal leaders. Findings suggested that training increased the manufacturing productivity of informal leaders. The increased productivity indicated that leadership training could help manufacturing facilities increase their productivity without capital expenditures. Findings did not indicate a statistically significant difference in leadership attributes. Findings also suggested there were no significant differences in the manufacturing productivity between employees with high leader attributes and low leader attributes. Based on this study, leadership training, given to non-management employees, may yield gains in manufacturing productivity.