Background: People with profound intellectual and multiple disabilities (PMLD) have communication impairments as one defining characteristic. Aims: To explore speech and language therapists' (SLTs) decision making in communication interventions for people with PMLD, in terms of the intervention approaches used, the factors informing the decisions to use specific interventions and the extent to which the rationales underpinning these decisions related to the components of evidence based practice (EBP), namely empirical evidence, clinical experience and client/carer views and values. Methods & Procedures: A questionnaire on communication assessment and intervention for people with PMLD was sent to SLTs in the UK to elicit information on: the communication intervention approaches they used; their rationales for their intervention choices; their use of published evidence to inform decision making. Outcomes & Results: Intensive interaction and objects of reference were the communication interventions most often used with people with PMLD, with some differences between children and adults evident. Rationales provided conformed somewhat to the EBP framework though extension of the existing framework and addition of practical and organizational considerations led to a revised typology of rationale for decision making. Rationales most frequently related to the empowerment, development and behavioural preferences of the person with PMLD. Conclusions & Implications: Empirical research evidence was seldom mentioned by SLTs as informing intervention decision making leading to very diverse practice. There is a need for further research on the effectiveness of commonly used but under-evaluated interventions. There is also a need to alert SLTs to the evidence base supporting other approaches, particularly switch-based, cause and effect approaches.