本文研究團體凝聚力的變化機制。研究一發現社區團體凝聚力的感受，會隨著洪水的嚴重程度而產生變化。也發現社區情感、社區認知、以及社區行爲可以預測社區團體的凝聚力，但是一般的人口變項則無顯著的預測能力。研究二則發現，凝聚力強的團體可以降低外力的干擾。跟凝聚力較強的團體比較起來時，凝聚力較弱的團體比較無法抵抗外力對團體效能所造成的影響、團體動能也比較差。本研究說明了團體凝聚力的變化過程，兩個研究的發現也有助於團體凝聚力的理論發展，本文最後並對專業經理人與團體領導者提出人事管理上的建言。

This project aims to investigate the changing mechanism of group cohesion. Study one indicated that perceived group cohesion in the com­munity varied subject to the flood severity. Group cohesion was predict­ed by the group affect, group cognition, and group behaviour, but not general demographical characteristics. Study two revealed that groups with strong cohesion were able to alleviate the influence of external forces on the group. Compared to their counterparts, groups with weaker cohesion were less likely to buffer the impact of external forces on group performance and dynamics. Both studies contribute to the theoretical framework of group cohesion by scrutinizing the process of cohesion variation. Implications of the findings and suggestions to managerial practitioners and group leaders are discussed.