There is a robust association between childhood maltreatment and later poor mental health. But what are the mechanisms that mediate this association? Recent functional imaging evidence indicates altered functioning in threat, reward, memory and emotion regulation systems in ostensibly ‘healthy' children who have experienced maltreatment. These alterations are similar to those seen in adults with presenting psychiatric disorders. I will introduce the concept of Latent Vulnerability as a framework within which we can understand these findings. Specifically, I will argue that maltreatment exposure can calibrate a child's psychological and biological systems in response to a threatening and unpredictable early environment in ways that may be adaptive in the short term but which confer long term psychiatric risk. Implications for intervention will be briefly considered, alongside a rationale for an increasing focus on preventative intervention.