Pai joined Enron in 1987, when it was just a regional energy supplier. He became one of (eventual) CEO Jeffrey Skilling's top lieutenants, primarily tasked with detailing and implementing Skilling's vision of transforming Enron into a "de facto" energy commodities-trading firm. During his Enron career, Skilling put Pai in charge of multiple Enron subsidiaries. Pai was CEO of the EES (Enron Energy Services) subsidiary from March 1997 until May 2001. The reasons for his resignation from Enron remain shrouded in mystery.