  The Gemini Planet Imager (GPI) is a next-generation, facility instrument
currently being commissioned at the Gemini South observatory. GPI combines an
extreme adaptive optics system and integral field spectrograph (IFS) with an
apodized-pupil Lyot coronagraph (APLC) producing an unprecedented capability
for directly imaging and spectroscopically characterizing extrasolar planets.
GPI's operating goal of $10^{-7}$ contrast requires very precise alignments
between the various elements of the coronagraph (two pupil masks and one focal
plane mask) and active control of the beam path throughout the instrument.
Here, we describe the techniques used to automatically align GPI and maintain
the alignment throughout the course of science observations. We discuss the
particular challenges of maintaining precision alignments on a Cassegrain
mounted instrument and strategies that we have developed that allow GPI to
achieve high contrast even in poor seeing conditions.
