The Free Energy Principle is the unified theory of brain function proposed by Karl Friston. The theory, in its generality is a provocative and controversial idea in neuroscience. It is a mathematical exposé on how neurobiological agents - human brains - are organised by one fundamental imperative - to minimise Free Energy. Its simplicity underpins its potential to understand how we perceive, move and behave. In this workshop, we are bringing together a group of scientists working either in support of the principle directly; it’s mathematical fundaments and biological plausibility, or with allied ideas – such as predictive coding. The workshop will include a didactic treatment of the core ideas of the theory, from variational Bayesian inference and hierarchical dynamic networks to neurobiological constructs. We will also explore how the ideas are informing new research into psychiatric disease. The workshop aims to provide a starter guide to scientists who would like to learn about the theory and employ it in their own work.