Speculation that adverse early life events can have a deleterious effect on the course of human development dates back at least 2 centuries. However, it was not until the second half of the 1900s that a causal link between early adversity and poor developmental outcomes was made, and it was not until the last 20 years that the biological mechanisms that may underpin this association have been identified. Advances in both neuroscience and genetics have increasingly shed light on how early experience “gets under the skin.” Whether we adopt the term developmental programming or biological embedding, the construct remains the same: early experience weaves its way into the neural and biological infrastructure of the child in such a way as to impact developmental trajectories and outcomes.