A significant concern of Road Authorities when considering public-private partnership as an option for providing highway facilities is how can they ensure that the highway is constructed and it operates as safely as a highway delivered in the conventional manner? The Ministry of Transportation of Ontario (MTO) had a similar concern when they were considering the sale of the Highway 407 corridor. Even though the agreement required that the facility be constructed and operated in accordance to MTO Standards, the question remained, how can it be ensured that the private operator was complying with this requirement? The answer to this question for the MTO has been Safety Auditing. Highway 407 has been open and operating for more than 10 years and it is one of the safest highways in North America. Safety Auditing has played a role in this success. The purpose of this paper is to present the Ministry of Transportation’s experience in using Auditing as a tool to ensure 407ETR’s safety compliance with the Concession and Ground Lease Agreement (CGLA).