This paper adapts Dye's (1995) model to evaluate the effects of the 150-hour rule on the audit market. Incorporating the auditors’ education as a joint input with the audit effort for determining the audit quality, we show that the audit fee is higher, pre-rule CPAs are better off, and audit clients are worse off as results of the Rule. Additionally, more pre-rule CPAs elect to enter the audit market. Some less wealthy post-rule CPAs who would otherwise get into the audit market choose not to. Surprisingly, the average audit quality in the market can be lower due to the Rule.