An augmentative and alternative communication (AAC) assessment is a complex, multidisciplinary process. Historic AAC assessment models have focused on treatment providing for basic communication needs more than on consideration of optimizing communication and maximizing an individual's potential. This paper presents an AAC assessment model based on the goal of interactive communication and a comprehensive evaluation of cognitive, linguistic, sensory and motor abilities that is evidence-based. We describe each component and assessment step within an evidence-based framework. The purpose is to offer a systematic, principled approach to selecting AAC assessment procedures in rehabilitation, speech language pathology and other related fields in order to strengthen their confidence in providing best possible services to clients who require AAC.