Luminous infrared galaxies have enhanced efficiencies of molecular cloud formation, and star formation, relative to normal galaxies with comparable total amounts of interstellar gas. The HI absorption and OH maser emission reveal high turbulent, non-circular motions in the nuclear regions of ultraluminous infrared galaxies. Outflow motions of the optical line-emitting nebulae are suggested by a statistical blueshift of the optical velocities relative to the radio velocities. Ultraluminous infrared galaxies are rapidly consuming their interstellar gas and represent a transient phase toward early type systems.