The present volume, Yoga Psychology, comprises the lectures on the Yogasutras of Rishi Patanjali in a systematic and scientific manner, with copious references and glossaries of Vyasa and Vachaspati Misra. They were delivered by Swami Abhedananda before a talented audience in America in 1920. The word ?Yoga? means the communion of the petty self with the higher universal Self, and ?psychology? is the science of the psyche or soul. The function of the psychology of Yoga is to prepare the mind, so as to catch a glimpse of the resplendent Atman, or to appreciate the real status and undying glory of the Absolute. The book discloses the secret of bringing under control the disturbing modifications of mind, and thus helps one to concentrate and meditate upon the transcendental Atman, which is the fountainhead of knowledge, intelligence and bliss.