In contentless experience there is an absence of mental content such as thought, perception, and mental imagery. The path to contentless experience in meditation can be taken to comprise the meditation technique, and the experiences on the way to the contentless “goal-state/s”. Shamatha, Transcendental, and Stillness Meditation are each said to access contentless experience, but the path to that experience in each practice is not yet well understood from a scientific perspective. We have employed evidence synthesis to select and review (...) 135 expert texts from those traditions. In this paper we describe the techniques and interim-states based on the expert texts and compare them across the practices on key dimensions. Superficially, Shamatha and Transcendental Meditation appear very different to Stillness Meditation in that they require bringing awareness to a meditation object. The more detailed and systematic approach taken in this paper indicates that posturally Shamatha is closer to Stillness Meditation, and that on several other dimensions Shamatha is quite different to both other practices. In particular, Shamatha involves greater measures to cultivate attentional stability and vividness with respect to an object, greater focusing, less tolerance of mind-wandering, more monitoring, and more deliberate doing/control. Achieving contentless experience in Shamatha is much slower, more difficult, and less frequent. The findings have important implications for taxonomies of meditation and for consciousness, neuroscientific, and clinical research/practice, and will provide new and useful insights for meditation practitioners. (shrink)