Abstract: Sustainability has become a crucial notion to be pursued throughout the life-cycles of project development, particularly during the post construction involving the Facility Management (FM) function. At the forefront of sustainable practice, FM professionals can apply a great deal of influence through operational and strategic management and therefore demand them to be empowered with the necessary knowledge, capabilities and skills. In the preliminary study reported separately, 23 critical people capabilities factors have been identified to support the sustainability measures in facility management practices. Through pairwise comparison study and Interpretive Structural Modelling (ISM) technique, this research further investigates the interrelationships between these critical factors, identifies the level of influences of each factor and propose a hierarchical structure that would enable FM professionals to take appropriate steps as an effective solution for the promotion of sustainable FM. The developed ISM Model shows that almost all of the people capability factors are interrelated and cannot be achieved in isolation. However, “familiar with the building system” factor and “understand the design and construction issues related to FM practice” factor have a high driving power and both of these factors contribute to the sustainability agenda in the strategic capability category. This analysis provides a directions for FM professionals to decide and differentiate between the independent and dependent factors and help them to focus on the enhancement of those people capability factors that are most important to support sustainable FM practices.