This final rule clarifies a provision included in recent amendments to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Specifically, today's final rule addresses the interim standard set by Congress in the Small Business Liability Relief and Brownfields Revitalization Act ("The Brownfields Law") for conducting "all appropriate inquiry." Today's action clarifies that, in the case of property purchased on or after May 31, 1997, the requirements for conducting "all appropriate inquiry," including the conduct of such activities to qualify as a bona fide prospective purchaser and to establish an innocent landowner defense under CERCLA, can be satisfied through the use of ASTM Standard E1527-00, entitled "Standard Practice for Environmental Site Assessment: Phase I Environmental Site Assessment Process." In addition, recipients of brownfields site assessment grants will be in compliance with the all appropriate inquiry requirements if they comply with either the ASTM Standard E1527-97, or the ASTM E1527-00 Standard.