sentences:  Accreditation by the American Association of Collegiate Schools of Business proved more elusive (and would not be granted until 1994), since Thunderbird did not then award the MBA degree, and indeed emphasized the "difference of degree" in its marketing materials.Over the 1970s and 1980s, enrollment rose to more than 1000, while Thunderbird's endowment also grew, reaching US$1 million in 1982 (and $20 million in the late 1990s).At the same time, Thunderbird began to experience competition from other American (and ultimately, foreign) business schools as international business increasingly became a mainstream subject.