The 200 most frequently used words cover 80% of our daily speech. These words are called Core Vocabulry. For students with communication disorders, especially with AAC needs, vocabulary selection is critical not only to their language and literacy development but also to their academic success. Having access to the most frequently used words eneble the students with communication disorders access to daily conversation in inclusive settings. Having a list of core vocabulary words, based on children´s natural speeches in different school activities, would be a helpful support for all professionals in the field of speech and language development. The first study in this presentation analyzes the core vocabulary use by 30 typically developing school-aged children (7-14 years) in the USA with English as first and second language. These results will be compared with a German core vocabulary study with cognitive disabled and non-disabled students (N=102, 7-16 years). All results show the enormous impact of core vocabulary for the language development in first and second language. Based on these results, new communication aids for students with severe communication disorders and new methods of teaching will be shown. Although the research and communication aids are focussed on students with complex communication needs to support more social and inclusive interaction, these results can also be used for refugees supporting their communication and language development.