There is now compelling evidence that children's early vocabulary development is essential to their long-term reading comprehension. Findings from experimental studies have indicated that vocabulary knowledge influences the development of conceptual knowledge and comprehension, suggesting a causal relationship among these fundamental language skills. Yet, profound differences in vocabulary knowledge among learners from different socioeconomic (SES) groups have been documented as early as toddlerhood. Given the strong evidence supporting early vocabulary instruction, there is a clear need to better understand how oral vocabulary instruction is enacted at the start of formal school and whether such instruction is equitable across socioeconomic circumstances. The purpose of this study was to develop a portrait of oral vocabulary instruction in kindergarten classrooms. The goal was to provide an in-depth description of the quantity and quality of oral vocabulary instruction provided by teachers serving in a range of SES contexts. The author's analysis revealed that vocabulary instruction in kindergarten consisted of single, brief word explanations by the teacher. The findings suggest that vocabulary instruction observed in a large group of kindergarten classrooms consisted of word explanations during teachable moments throughout the day with no evidence of more formal vocabulary instruction. The author found that teachers serving in economically advantaged schools provided more of these teachable moments and addressed more challenging words than teachers serving in predominantly low-income schools.