Abstract: Stars of all masses form in dense clouds of molecular gas. They begin life as a protostar; a warm ball of gas and dust heated by thermal pressure. For more than a million years, the protostar gains material through an accretion disk which regulates the accretion rate onto the star and directs high angular momentum material into spectacular molecular and ionized outflows. Disks and molecular outflows in the form of wide-angle winds and/or well-collimated jets are associatedwith protostars of all luminosities. Because outflows provide record of the mass-loss history of the system, they can be useful tools to help understand the underlying formation processes of young stars. There is reasonable evidence that accretion-related processes are responsible for generating massive molecular flows from protostars up to spectral type B0 (10-15 Msun). Above a luminosity of 10,000 L sun, O stars generate powerful wide-angle, ionized winds that dramatically affect outflow morphology and even call into question the relationship between outflow and accretion. Recently Beuther & Shepherd proposed an evolutionary scenario in which massive protostellar flows begin collimated. Once the star reaches the Main Sequence, the ionizing radiation affects the balance between magnetic and plasma pressure, inducing changes in the flow morphology and energetics. I will review the known properties of outflows from young, massive OB stars, discuss implications and observational tests of this proposed evolutionary scenario, and examine differences between low-mass and massive star formation.