Looking beyond the current generation of 8 and 10 meter diameter ground-based optical and infrared telescopes, a public-private partnership of the Association of Universities for Research in Astronomy (AURA), the Association of Canadian Universities for Research in Astronomy (ACURA), Caltech, and the University of California is developing the design of a 30 meter diameter telescope. A thirty meter telescope will have 144 times the light collection and sharper optical resolution than the Hubble Space Telescope, and 9 times the light collection of the 10 meter Keck telescopes. The decadal survey of astronomy has ranked such a telescope as the highest priority in ground-based astronomy. Construction of the TMT is planned to bring the observatory into operation in the middle of the next decade, overlapping observing with the James Webb Space Telescope and ALMA. Among the scientific goals for TMT is the origin of large scale structure in the universe, the assembly of galaxies in the early universe (z>3), the formation and characterization of extrasolar planets, and processes governing star and planet formation. The science goals and requirements, the telescope conceptual design, the program to identify a suitable observatory site and the planning for science instruments and astronomy community involvement in TMT will be described.