This chapter describes the various stages of lexical retrieval process, their biolinguistic bases and neural correlates, and the patterns of acquired and developmental anomias that result from selective deficits in each of the stages. It also describes various types of anomia. The chapter focuses on the characteristics of selective anomias, namely, what happens when an individual has a single deficit along the lexical retrieval process. Semantic errors occur both in a semantic lexicon impairment and in a phonological lexicon impairment. To demonstrate how children and adolescents with lexical retrieval impairments may be classified into the different anomia patterns, the chapter presents four case studies, whose loci of impairment are summarized. There are several methods to map the functional components of lexical retrieval onto specific brain locations. One group of methods assesses brain activations in the healthy brain; the other assesses brain areas in individuals with anomia.