We explored the value of a battery of socioemotional tasks for differentiating between frontotemporal lobar degeneration (FTLD) and Alzheimer's disease (AD). Patients with FTLD (n = 13) or AD (n = 13) and healthy controls (n = 26) underwent a neuropsychological assessment and the socioemotional battery (an empathy questionnaire, an emotion recognition task, and theory of mind tasks). Socioemotional processes were markedly impaired in FTLD but relatively unaffected in mild AD. The computed Socioemotional Index discriminated more accurately between FTLD from AD than behavioral and executive assessments did. Furthermore, impairments in socioemotional processes were correlated with indifference to others.