Karma Yoga: The Yoga of action is a book of lectures by Swami Vivekananda, as transcribed by Joseph Josiah Goodwin.
The main subject of the book is Karma (Work) and Karma Yoga (The Yoga of Action). Vivekananda uses the concept of Karma as described in the Bhagavad Gita to explain his philosophy.
The final message is that work is worship and a path to enlightenment.