A new general purpose detector, BESIII, is under construction for the Beijing Electron Positron Collider II (BEPCII). The design, R&D, and manufacture of BESIII are described. The talk will cover in detail the time of flight system, which is composed of plastic scintillator directly coupled with fine-mesh photo multiplier tubes. It's main purpose is particle identification, in particular the separation of pions and kaons, which requires good time resolution of 90 ps. Details of the TOF design, space alignment, beam tests, photomultipier tests, scintillator tests, wrapping material tests, preamps, front end electronics, quality control, and the project schedule will be described.
