When the relationship between the independent variable and the dependent variable becomes contingent on another variable that has a moderating effect on this relationship, this variable is called as a moderating variable (Sekaran, 2003, p. 91). This study argues that the organization members’ support moderates: (1) the relationship between internal auditor’s characteristics and internal audit effectiveness, and (2) the relationship between internal audit department performance and internal audit effectiveness. In other words, internal audit effectiveness could be reached only when the activities of both internal audit and its auditors are supported by organization members. This support includes allocating adequate human and material resources to internal audit for instance, and the overall tone in the organization of acceptance and appreciation both internal audit and its auditors, and to implement internal audit recommendations. However, no attention has been given, in prior literature, to examine the impact of organization members’ support as a moderating variable. Therefore, consistent with the logical connections above, the current study expects those organization members’ support moderates the independent variable-dependent variable relationship as it is perceived by external auditors significantly. Figure 1 shows the theoretical framework of internal audit effectiveness.