Dementia syndromes can include language impairments (LIs) of severity extending from lexical access difficulties within anomic aphasia to non-fluent effortful speech and semantic aphasia, depending on the stage and etiology of the underlying disease. Relevant etiologies include neurodegenerative Alzheimer’s disease (AD) and non-AD dementias, such as frontotemporal lobar degeneration (FTD), Parkinson’s (PD) and Lewy body diseases, vascular and toxic alcohol-related dementia, depressive pseudodementia and mixed type dementia. Irrespective of the underlying disease, LIs interfere with social contacts and personal relationships, thus substantially reducing the quality of life and daily functioning of patients, while increasing their need for supervision and care. Socio-linguistic discourse describes such patients as experiencing “loss of self”, “no meaningful present”, “active presence of the past in the body itself”, and as the “long goodbye” (Snyder in Dementia: Mind, meaning and the person, Oxford University Press, p. 268, 2006), highlighting the stigmatization and low quality of life of dementia sufferers. In this chapter we summarize the similarities and differences in clinical and linguistic presentations of LIs in AD and the most commonly occurring types of non-AD dementias, emphasizing the decisive diagnostic and prognostic roles of LIs, as well as their implications for choice of treatment. We present an account of the neuropsychological and psycholinguistic approaches to assess LIs occurring in dementia through evaluation of language functions/domains, such as sound-based domain and lexis (naming, reading, writing), syntax (repeating, composing sentences), and semantics, pragmatics, and discourse (comprehension—auditory, semantic knowledge, understanding commands). We discuss research findings on the protective properties of cognitive reserve, second language acquisition (L2), and multilingualism, all of which can delay the onset of dementia symptoms. We make note of the available interventions in the management of LIs, which include pharmacotherapy (acetylcholinesterase inhibitors such as donezepil, galantamine, and rivastigmine), cognitive interventions (lexical-semantic therapy, action-language therapy, language socialization), and other options of person-centered care (e.g., narrative care). We also review the benefits of destigmatization activities that can be obtained through building a dementia-friendly community environment.