Spirituality is gaining increasing recognition as a legitimate and necessary aspect of psychological health, with a literature that, if not covertly selling an ideology, has traditionally been either overly simplistic so as to seem naive or, alternatively, so complex that a prior knowledge is needed. This work, however, is written in an accessible style that appeals to the general reader as well as experienced clinician. It presents an in-depth and critical exploration of transpersonal thinking in relationship to helping professions with a broad yet detailed overview of transpersonal theory and its place in clinical practice. It examines the work of newer and established transpersonal theorists and the influence that the transpersonal perspective has had upon the major schools of psychology. Furthermore, it also considers the effect that other bodies within the humanities, such as philosophy and esoteric thought, bring to bear on the transpersonal school as well as the insights from bodies of knowledge in the hard sciences, such as neuro-biology and quantum physics.