Gallium oxide (Ga₂O₃) is an emerging ultra-wide band gap semiconductor that is attracting growing interest for high-efficiency electronics that can operate in extreme conditions, such as high-power/high-frequency/high-temperature electronics and optoelectronics operating in the ultraviolet region. The existence of different phases, or polymorphs, of Ga₂O₃ presents both a challenge and an opportunity to fabricate highly ordered Ga₂O₃ films with control over phase, microstructure and morphology. The monoclinic β-Ga₂O₃ phase is the thermodynamically stable polymorph at atmospheric conditions up to its melting point and is the one most investigated. The other phases (in epitaxial form) are also of interest, as their crystal structures have higher symmetry and all are ultra-wide bandgap semiconductors. These metastable polymorphs also possess unique properties (e.g., high spontaneous polarization / ferroelectricity) that can extend the types of devices based on Ga₂O₃. Furthermore, the ability to grow different Ga₂O₃ polymorphs presents opportunities to modulate bandgaps of structurally-matched (In,Ga,Al)₂O₃ ternary alloys (from In₂O₃ (E_g = 3.7 eV) to Al₂O₃ (E_g = 8.8 eV)). In this presentation the unique properties and attributes of Ga₂O₃ phases of interest for devices will be presented, as will our results on MOCVD growth of epitaxial films of phase-pure vs. mixed-phase Ga₂O₃ polymorphs. Specifically, we will report on variables (e.g., temperature, TEGa flow rate, and substrate) that we have used to achieve unprecedented control over the resulting polymorph. We will also show our characterization results of phase composition, microstructure, and morphology using x-ray diffraction, scanning electron microscopy, and high-resolution scanning transmission electron microscopy.