The philologists and cultural commentators who first introduced the word Buddhism into the English lexicon intended it to refer to a “world religion” that was eminently psychological in nature. Finding in Buddhist texts intricate treatises on the function of mentation or on classificatory systems of human cognition, early European and US translators such as Thomas Rhys Davids defined Buddhism as an “ethical psychology.” Through the 19th century, Asian Buddhist leaders from the Japanese monk Shaku Soen to the Sri Lankan/Ceylonese Anagārika Dharmapāla sought to legitimate Buddhist doctrine with appeals to the language of the psychological. Their interlocutors in Europe and the United States, including figures such as Paul Carus, explicitly attempted to align Buddhist doctrine not only with rationalist scientific truth but, in particular, with the then-nascent discipline of psychology. When psychologists and psychotherapists began to examine Buddhist teachings and practice, they thus presumed they would find a protopsychology. Early psychologists of religion such as James Bissett Pratt were predisposed to conclude that “Gotama Buddha was probably the greatest psychologist of his age.” The first psychoanalysts to take an interest in Buddhist traditions likewise assumed that Buddhist practices of a putative “self-absorption” were ancient esoteric means for what Carl Jung called a “penetration into the groundlayers of consciousness.” Jung further pronounced his analytical psychology to have revealed that Buddhist “enlightenment” was, in actuality, a form of psychotherapeutic self-actualization, an idea that frequently resurfaced in later psychological interpretations of Buddhist traditions. Into the early 1960s, Buddhist religious figures such as D. T. Suzuki worked directly with psychological interpreters, including the humanistic psychoanalyst Erich Fromm. In these conversations, Suzuki further advanced ideas such as that Zen Buddhist practices accessed otherwise unreachable depths of the unconscious. As Buddhist communities populated predominantly by so-called “converts” of European descent developed in the United States, they were often based on doctrine that interpreted concepts such as rebirth in psychological terms. Through the 1990s, Buddhist meditative states continued to be the object of psychological and neuropsychological research and experimentation, often with the participation of major Buddhist figures such as the Dalai Lama. And although earlier psychotherapists largely compared psychological and Buddhist frames as a theoretical matter, Buddhist elements began to be increasingly incorporated into actual clinical work. Such activities are perhaps most prominently represented by the ubiquitous use of therapeutic mindfulness practices, but psychotherapists have been influenced by a wide diversity of teachings and practices drawn from diverse contemporary Buddhist communities. Those communities have long been shaped by the idea that a Buddhist path is uniquely psychological, but, strikingly, some have also been founded and led by individuals such as Jack Kornfield or Barry Magid who hold dual roles as psychologists and psychotherapists.