The repertoire of human imaginative thought is incredibly large. Whether reminiscing on memorable past experiences, or entertaining our hypothetical futures; whether transporting ourselves into a good book, or listening to an engaging conversation; whether reasoning about the thoughts of others, or pondering the meaning of life – the human mind is constantly imagining that which lies beyond our current sensory input. In this chapter, we aim to introduce a neuroscience-informed framework by which the diverse array of imaginative thoughts can be functionally organized. We first review some key psychological ingredients of imaginative thought: their content, their level of abstraction, their mode of representation, and the ways in which they arise and unfold over time. Next, we propose a neural basis for these different elements based on research highlighting the role of the brain’s default network in aspects of imagination. Third, we propose an integrative model whereby imaginative thoughts can be divided into two broad classes that often interact in everyday experience and in the brain: one encompassing contextually rich, perceptually vivid mental simulations, and another encompassing conceptually abstract, often verbal modes of imagination. We hope this neurocognitive framework will help organize the many varieties of imagination and facilitate cross-disciplinary collaboration and discovery.