The development of the commercialization of 2,6-naphthalenedicarboxylic acid (2,6-NDA), dimethyl-2,6-naphthalenedicarboxylate (2,6-NDC) and their homopolymer with ethylene glycol, polyethylene naphthalate (PEN), is reviewed. Many of the significant alternative chemical routes to produce 2,6-dimethylnaphthalene (2,6-DMN), the main precursor to 2,6-NDA, are discussed and evaluated. The o-xylene + butadiene multi-step route of BP Amoco's first-in-the- world large scale commercial plant built in Decatur, Alabama is described. Production economics of some of the major 2,6-NDC precursors are described. Physical properties of the 2,6-DMN intermediates, 2,6-NDA and 2,6-NDC. are given along with some discussion on the methods of purification of the dibasic naphthalate monomers. Polymer applications for PEN and manufacturing economics of PEN versus PET are compared, and finally, engineering resins incorporating 2,6-NDA and 2,6-NDC are described.