This chapter will discuss certification (and, to a lesser extent, collective) marks, which comprise an increasingly important proportion of marks in use within interstate and international commerce.1 Unlike trademarks and service marks, which serve primarily as indicators of source, certification marks have other acknowledged functions in trademark law and policy. For example, certification marks in the United States exist “to certify regional or other origin, material, mode of manufacture, quality, accuracy, or other characteristics of such person’s goods or services or that the work or labor on the goods or services was performed by members of a union or other organization.”2 According to the US Patent and Trademark Office (USPTO), “a certification mark … inform[s] purchasers that the goods or services of a person possess certain characteristics or meet certain qualifications or standards established by another person. [It] does not indicate origin in a single commercial or proprietary source the way a trademark or service mark does.”3