Our current view of the interstellar medium (ISM) is as a multiphase environment where magnetohydrodynamic (MHD) turbulence affects many key processes: star formation, cosmic ray acceleration, and the evolution of structure in the diffuse ISM. In part 1 of this talk, I shall review the fundamentals of galactic turbulence and discuss progress in the development of new techniques for comparing observational data with numerical MHD turbulence simulations. In part 2, I will focus on how turbulence affects the long-standing problem of star formation. From scales of giant molecular clouds (GMCs), I will demonstrate how the star formation efficiency can be analytically calculated from our understanding of how turbulence, gravity, and stellar feedback induce density fluctuations in the ISM via a probability distribution function analysis. This analytic calculation predicts star formation rates from pc size scales (GMCs) to kpc size scales in galaxies.