Effective internal control is a foundation for the safe and sound operation of companies. An important element in assessing the effectiveness of the internal control system is an internal audit function. Each company should have an internal audit function that is appropriate to its size and the scope of its activities. In addressing various quality and resource issues, many companies have been engaging independent public accounting firms and other outside professionals (outsourcing vendors) in recent years to perform work that traditionally has been done by internal auditors. These arrangements are often called “internal audit outsourcing,” “internal audit assistance,” “audit co-sourcing,” and “extended audit services” (hereafter collectively referred to as outsourcing).