The acquisition of vocabulary is an important aspect of young children's development that may impact their later literacy skills (National Reading Panel, 2000; Cunningham & Stanovitch, 1997). Deaf children who are American Sign Language users, however, often have smaller vocabularies and lower literacy levels than their hearing peers (Lederberg & Prezbindowski, 2001; Schirmer & McGough, 2005). Despite the importance of teaching vocabulary for young deaf children, there are very few investigations on this important topic (Luckner & Cooke, 2010). This study examines the nature of vocabulary instruction by four early childhood teachers of deaf children (TODs) from two classrooms through a qualitative collective case study. Findings indicated that the Four-Part Vocabulary Program (Graves, 2006) could account for the nature of vocabulary in these classrooms; however, within this framework TODs used qualitatively different language strategies to address the unique aspects of teaching a visual language. Furthermore, there was interplay of teacher knowledge about learners, curricula, and pedagogy that informed their instructional planning and decision-making. Implications of this study include the varying roles of teacher knowledge, experience, and evidence in guiding ASL vocabulary instruction for TODs. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]