An ocular implant delivery system is provided with a number of features. In some embodiments, the delivery system comprises a rotation mechanism configured to rotate and orient a cannula of the system, and an advancement mechanism configured to advance and retract an ocular implant through the delivery system and into an eye of a patient. In some embodiments, the cannula is sized and configured to be inserted into Schlemm's canal of the eye. The ocular implant is configured to maintain its orientation within the delivery system as the cannula is rotated. In some embodiments, the ocular implant automatically disengages the delivery system when it is advanced beyond a distal tip of the delivery system. Methods of implanting an ocular implant are also provided.