Both c-plane surfaces of bulk GaN crystals were examined using reflection high-energy electron diffraction (RHEED). Differences in the RHEED pattern, time development of the RHEED intensity, and surface reconstructions were observed. On GaN(0001), or GaN-B, the Ga rich reconstructions reported by Smith and coworkers were observed. On GaN(0001), or GaN-A, a (2×2) reconstruction was observed. RHEED measurements of the specular intensity vs time showed that two different surface terminations could be maintained on the B surface, one of which is a stable, gallided surface, while the other is a nitrided surface, which is unstable in vacuum. If the nitrided surface is heated in vacuum it changes to the gallided surface in several minutes at 800oC. Only one termination was detected on the A surface. The results are complemented by desorption mass spectroscopy (DMS) measurements, and the resulting surfaces were then investigated using atomic force microscopy (AFM) and Scanning Tunneling Microscopy (STM). Two surface terminations were distinguished on the B surface, and a unique annealing process under NH3 will be documented. Preliminary investigation of the A surface revealed decorated step edges. The results were compared to films grown on sapphire with different nucleation layers, which can be grown to yield either polarity. Focusing on the GaN-B polarity, the surface reactivity and growth kinetics are investigated as a function of growth parameters using DMS. Growth proceeds either by island nucleation or by step flow, depending on the steady state surface coverage of Ga. Three Ga adsorption sites are found on the surface, one chemisorption and two physisorption sites. One of the physisorption sites corresponds to an extrinsic precursor state, while the other corresponds to an intrinsic precursor state with a very short residence time. An abrupt growth mode transition is found as a function of growth parameters between island nucleation and step flow, which is directly related to the coverage of chemisorbed Ga at steady state. A quantitative model is developed for this GaN-B surface which explains the transitional Ga uptake, steady state growth, as well as the abrupt transition between growth modes.