Educational practices are needed to promote strong vocabulary growth so that vocabulary can be both the cause and result of successful reading. Vocabulary interventions need to begin early and continue for a sustained period of time (Beck & McKeown, 2007a; Biemiller, 2003; Foorman, Seals, Anthony & Pollard-Durodola, 2003). According to theoretical and empirical research, there are three components of vocabulary instruction that are needed to boost vocabulary growth and improve reading. A number of literature reviews have concluded that successful vocabulary instruction includes: (1) both definitional and contextual information, (2) more than one or two exposures to each word, and (3) engagement of students in deep processing about word meaning and use (Baumann, Kameenui, & Ash, 2003; Beck, McKeown & Kucan, 2002; Blachowicz & Fisher, 2000; Mezynski, 1983; Nagy & Scott, 2000; Rupley & Nichols, 2005; Stahl & Fairbanks, 1986). "Elements of Reading[R]: Vocabulary" ("EOR-V") (Beck & McKeown, 2004) is an instructional intervention that was designed to incorporate these three components and be used daily by classroom teachers to supplement core reading instruction. The purpose of this study was to provide unbiased estimates of the effects of robust vocabulary instruction as instantiated in "EOR-V" in schools serving children from low-income households. Vocabulary researchers recognize that word learning does not occur easily or quickly (McKeown, Beck, Omanson & Pople, 1985; White, Graves & Slater, 1990). Children need early, more and continuous robust vocabulary instruction to develop a vocabulary of sophisticated words (Beck & McKeown, 2007a). The research addressed this need by testing the effects of a full, one- and two-year implementation of "EOR-V" on both vocabulary and reading comprehension. The specific purpose of the proposed presentation is to report estimates of the proximal effects of "EOR-V" on vocabulary and listening or reading comprehension as evaluated at the end of the first year of the two-year intervention. Results for adherence to program elements demonstrate that not all elements were used to a high level. However, lessons were still significantly different from control classrooms as demonstrated by the Depth of Processing analysis of classroom discussion. Results for dosage indicated that many teachers used only half the available lessons. Yet, despite the low dosage and the less than ideal adherence fidelity, the intervention still seemed effective enough to promote significant differences in achievement in both knowledge of the target words and comprehension using the target words at both primary and intermediate grade levels. The magnitude of the present proximal effects on vocabulary was as great as or greater than the average proximal effect reported for vocabulary interventions (0.79) in a recent meta-analysis (Elleman, Lindo, Morphy & Compton, 2009). Findings confirm recommendations for vocabulary instruction that provides multiple contexts and engages students' processing of meaning to achieve the goals of increased vocabulary knowledge and comprehension. The findings demonstrate that such recommendations apply to primary and intermediate grades students. Further, findings suggest that expected knowledge and comprehension results can occur even when implementation is less intense than usually prescribed. (Contains 5 tables.)