The chapter focuses on the scientific assessment of the emotional experience of pain in farmed animals. A variety of methods allow for insights regarding the issue to felt pain and how much this matters to the animal. These include simple behavioural responses (such as avoidance, body movements and vocalizations), as well as more sophisticated behavioural tests that allow for stronger inferences regarding the emotional component of pain. Some painful experiences can have more persistent effects on animals, resulting in negative mood states. These long-lasting negative affective experiences are of obvious interest when seeking to understand the impact of pain on animal welfare as negative mood means that future experiences are more likely to be experienced negatively. The expectations that animals form regarding pain experiences may make painful experiences even more unpleasant for animals, and a combination of painful experiences and other factors related to the context of the experience (including expectations) may result in suffering, especially when animals are also experiencing fear and have little control over what they experience. Negative experiences (such as pain and fear) may reset what animals expect, setting up a potential cascade of negative experiences; alternatively, the use of positive reinforcement training can mitigate negative expectations in a way that reduces the risk of suffering in farmed animals.