Aphasia is an acquired language disorder resulting from damage to the brain, most typically a stroke in the left cerebral hemisphere. The degree and type of impairment vary depending on the site and size of the lesion, and the extent to which people with aphasia recover – with time and therapeutic intervention – their pre-stroke linguistic skills varies, depending on exogenous and endogenous variables. Multilingual speakers who acquire aphasia may exhibit comparable or different profiles of impairment in each of their languages. The present chapter explores the challenges associated with the assessment of all languages of multilingual and multicultural speakers with aphasia. These challenges include four broad categories: 1) Individual differences; 2) Availability of clinicians who speak the relevant languages and who are trained to work with multilingual and multicultural individuals, as well as availability of qualified and trained interpreters; 3) Availability of linguistically and culturally appropriate assessment tools; 4) The complexity of interpreting data elicited from multilingual individuals with aphasia, including mixed-language production and errors that could be associated with the aphasia as well as with limited pre-onset language proficiency. The chapter concludes with a discussion of preliminary solutions and future directions for the practice of assessing multilingual individuals with acquired communication disorders, and the value of considering all their languages in the assessment and rehabilitation practices.