This study's goal was to inform the selection of the most frequently used words to serve as a reference for core vocabulary selection for Hebrew-speaking children who require AAC. The paper describes the vocabulary used by 12 Hebrew-speaking preschool children with typical development in two different conditions: peer talk, and peer talk with adult mediation. Language samples were audio-recorded, transcribed, and analyzed using the CHILDES (Child Language Data Exchange System) tools to identify the most frequently used words. The top 200 lexemes (all variations of a single word) in the peer talk and adult-mediated peer talk conditions accounted for 87.15% (n = 5008 tokens) and 86.4% (n = 5331 tokens) of the total tokens produced in each language sample (n = 5746, n = 6168), respectively. A substantially overlapping vocabulary of 337 lexemes accounted for up to 87% (n = 10411) of the tokens produced in the composite list (n = 11914). The results indicate that a relatively small set of words represent a large proportion of the words used by the preschoolers across two different conditions. General versus language-specific implications for core vocabulary selection for children in need of AAC devices are discussed.