Research has demonstrated that approximately one third of Amyotrophic Lateral Sclerosis (ALS) patients exhibit subtle changes in cognition and social and emotional behaviours, similar to those seen in the behavioural variant of frontotemporal dementia (bvFTD). Arguably, such problems may arise from a difficulty in interpreting social signals. This study investigated whether ALS patients have a specific impairment of affective Theory of Mind (ToM). Nine non-demented ALS patients and 16 age and education matched controls undertook tests of social cognition: a ‘Judgement of Preference based on Eye Gaze’ task, with both cognitive and affective conditions and the Reading the Mind in the Eyes (RME) task. Participants also completed behavioural questionnaires: the Frontal Systems Behavioural Scale (FrSBe), the Interpersonal Reactivity Index (IRI) and the Emotional Lability Questionnaire (ELQ) along with standard neuropsychological tests of cognitive and executive function. While no group differences were observed in the ToM tasks, one patient exhibited the hypothesised deficit in the affective condition of the Judgement of Preference task and one was impaired in the RME task. ALS patients had significantly more behavioural abnormalities than controls, and compared to premorbid ratings, as well as symptoms of emotional lability. However no deficit of empathy was observed in the ALS groups, nor in any individual patient. Correlation analysis found a slight relationship between the Judgement of Preference scores and self-rated executive dysfunction but not with any other behavioural measures. Comparison of self- and carer-rated versions of the questionnaires revealed a pattern of higher ratings by patients than carers, suggesting that non-demented ALS patients have insight into changes in their behaviour.