Communication vulnerable children need an alternative way to express their pain to receive appropriate pain management. In this chapter, the concept of communication vulnerability will be explained by using the social-communication model of pain as a theoretical framework. The concept of pain is difficult to describe due to its subjective nature and individuals’ different experiences to pain. Clinicians and researchers find it challenging to understand the dynamic interplay between the biological, psychological and social determinants of pain. Understanding any episode of acute or chronic pain therefore necessitates considering the holistic pain picture to analyse the essentials at biological, psychological and social levels. The chapter concludes with suggestions to use augmentative and alternative strategies to support communication vulnerable children to communicate their pain.