Background: Aphasia assessment is traditionally divided into formal and informal approaches. Informal assessment is useful in developing a rich understanding of the person with aphasia's performance, e.g., describing performance in the context of real-world activities, and exploring the impact of environmental and/or partner supports upon communication. However, defining 'informal assessment' is problematic and can result in clinical issues including idiosyncratic practices regarding why, when and how to apply informal assessment. Aims: To examine the extent to which the informal assessment literature can guide speech and language therapists (SLTs) in their clinical application of informal assessment for post-stroke aphasia. Methods & Procedures: A scoping review methodology was used. A systematic search of electronic databases (Scopus, Embase, PyscInfo, CINAHL, Ovid Medline and AMED) gave informal assessment references between 2000 and 2017 to which title/abstract and full-text screening against inclusion criteria were applied. Data were extracted from 28 resulting documents using an extraction template with fields based on the review's purpose. Main Contribution: This review examines the informal assessment guidance regarding: rationale; areas of interest for informal assessment; available methods; procedural guidance; documentation; and analytical frameworks. The rationale for using informal assessment included several aspects such as gaining a 'representative' sample of the individual's language. Ten communication areas of interest were found with 13 different assessment methods. The procedural guidance for these methods varied considerably, with the exception of conversation and semi-structured interviewing. Overall, documentation guidance was limited but numerous analytical frameworks were found. Conclusions: Several informal assessment methods are available to SLTs. However, information is mixed regarding when they might be used or how they might be applied in terms of their administration, documentation and analysis.