Communication disorders are a problem for people around the world. However, language disorders are rarely studied within the context of bilingualism. This is despite the fact that the majority of individuals who are affected by acquired language disorders are multilingual. Studies of bilingual aphasic speakers reveal important insights about the cognitive and neurological factors involved in multilingualism and have an impact on the assessment and the rehabilitation of aphasic speakers. The aim of this Special Issue is to present papers by leading researchers in the field of aphasia and to examine the patterns of speech and language disorders among speakers who have varying proficiency in their native and non-native languages.