Background: Assessment of communication for people with communication problems following stroke should be socially valid; it should encompass activities relevant to the speaker's environment and the opinion of people within that environment. Potentially relevant opinions include those of the person with the communication problem and their close carers/companions. When compared to the evaluations of healthcare providers (here speech and language therapists) there may be differences between the professional and "non-professional" opinions, and also between the carers and service users. Differences may be due to levels of familiarity with the speaker, experience of their communication in different situations, differing perceptions of the impact of the problem, or potentially the ability of people with communication problems to engage with the assessment materials. Aims: The study aimed to compare speakers', carers', and speech and language therapists' perspectives of stroke survivors' functional communication; to examine the effect of severity of aphasia on levels of agreement. Methods & Procedures: Participants were (a) 98 people who had communication problems (aphasia and/or dysarthria) following a stroke; (b) 56 of their carers; (c) speech and language therapists who were specialists in this field. Stroke survivors and carers rated communication on the parallel COAST and Carer COAST scales; SLTs rated a 10-minute videoed sample of conversation between the person with communication problems and an unfamiliar facilitative partner, using the aphasia/dysarthria activity scale of the Therapy Outcome Measure (TOM). Analysis included correlation, percent total and close agreement, and exploration of individual scale items. Outcomes & Results: Good agreement was shown between speakers and carers using the COAST and Carer COAST.Moderate agreement was shown between both these and the SLT TOMratings. Severity affected level of agreement to some extent; there was a moderate negative correlation between stroke survivor-carer difference in ratings and the stroke survivor's score on the Frenchay Aphasia Screening Test. Conclusions: Similarity in the stroke survivor and carer views was revealed by COAST and Carer COAST. However, both may differ from the opinion of the SLT. It is possible for assessment of functional communication to capture different perspectives that are each important and should not be expected to be identical. Therapists should focus on exploring the reasons for the different perceptions and working through the implications for their intervention. © 2010 Psychology Press.