One of the observed phenomena in the current highly competitive business environment is the growing complexity of business models and their operations. Consequently, external users of corporate financial statements are increasingly relying on external auditors to assure them that the financial information disclosed in corporate financial statements is reliable. However, external users of financial statements may have a different understanding of the nature, limitations, assurance level, and responsibility of auditors which is called Audit Expectation Gap. “In the wake of the financial crisis, investors are particularly angry that audit reports do nothing to forewarn investors when a company is in dire financial straits. While auditors most certainly did not cause the financial crisis, some people have legitimately questioned whether audits adequately served investors' needs in the months and years before and during the crisis,” (James Doty Chairman of PCAOB, 2011). In current book, audit expectation gap, its different definitions, potential reasons, the factors that may influence it and different ways to mitigate it, are discussed.