This chapter reviews assessing emotions in pigs, specifically focusing on the ways of determining negative and positive mental states. It begins by examining behavioural indicators of emotion such as behavioural tests, qualitative behaviour assessment, vocalisations, play behaviour, defence cascade responses and facial expression and body posture. The chapter also assesses cognitive indicators of emotion in pigs and judgement bias. This is followed by a discussion of neurophysiological indicators of emotion in pigs, focusing specifically on the physiology of negative and positive emotions.