Under ideal circumstances, the resolution of an optical system is limited by the diffraction of light waves. In practice, this limit is never achieved at ground-based telescopes because of atmospheric turbulence blurring the images. Adaptive optics (AO) provides a means of compensating for these effects, leading to sharper images, sometimes approaching the theoretical diffraction limit. Lick Observatory and the Center for Adaptive Optics are at the forefront of the field in designing and applying AO systems. I will describe the Sodium Laser Guide Star Adaptive Optics instrument at Lick Observatory, currently the only sodium beacon being used for science, as well as some of the current research results from the AO program.