The child's interactions with persons in the proximal environment constitute the context for development of communication. Within early close relationships, the child acquires communication skills; developmental outcomes are defined by the continuous dynamic interactions of the child, the experiences provided by the family and close environment, and the use of different means of augmentative and alternative communication (AAC). Communication problems manifest in a variety of ways and at different levels of severity. The nature of problems differs as a function of the child's age and diagnosed condition, the communication skills of interaction partners, and the availability of communication aids. The focus for assessment and intervention may be the child, the family, the close environment and/or the interactions between them. Clarifying these varied functions and environmental factors is crucial for appropriate assessment and provision of augmentative and alternative communication (AAC) interventions. This paper reviews issues in assessment and intervention for children in need of AAC and presents the World Health Organizations' (WHO) International Classification of Functioning, Disability and Health version for Children and Youth (ICF-CY) as a tool to enhance assessment and intervention in the AAC field.