Using an intensive ecological momentary assessment design, the authors found that vivid “flash-forward” mental images of self-harm frequently occurred when NSSI urges were high and often depicted the actions, sensations, and anticipated emotional relief associated with self-injury. Importantly, these mental images predicted increases in future NSSI urges and a greater likelihood of acting on those urges, even after accounting for current urge intensity. The findings suggest that self-harm imagery may be more than a by-product of distress and instead function as a motivational driver of behaviour. Overall, the study highlights mental imagery as a potentially modifiable intervention target for reducing self-harm risk.