This study tested the validity of Vroom and Jago's (1988) new leadership theory—proposed to overcome the limitations of Vroom and Yetton's (1973) leadership theory—using a sample of 140 section chief-level managers in Korean firms. The managers were asked to analyze the content of official correspondence they needed to process as a problem to be solved, examining it according to the 11 situational variables (excluding geographic dispersion from the original 12) specified by the model, and to select one decision-making method (AI through GII) they wished to use in processing the correspondence. After each manager actually processed their selected correspondence (approximately two weeks later), they evaluated the results of the problem resolution (processed correspondence) along the dimensions of effectiveness, quality, commitment (acceptance), subordinate development, time cost, and time penalty. Correlation analyses were then conducted between these evaluations and the values computed through the model's equations. Additionally, the processed correspondence results were sent to superiors (department heads) and subordinates (assistant managers) for evaluation of decision-making effectiveness. The analysis results showed that all expected correlations were significant, thereby validating the Vroom/Jago theory.