Given the increase of bilingual students in the K-12 public school system, understanding reading comprehension performance, especially among this population, has been a major focal point in the research literature. This study explores the nature of reading comprehension among a sample of 123 Spanish-English bilingual elementary students. We add to the existing knowledge base regarding reading comprehension in two significant ways: (1) augmenting the Simple View of Reading by testing the role of both vocabulary depth contribution and dual-linguistic ability in English reading comprehension; and (2) questioning the manner through which reading comprehension is understood through measurement and conceptualization. Specifically, we build a comprehensive model of reading comprehension that tests the effects for vocabulary depth, Spanish oral language, and biliteracy. In line with previous research that suggests different reading measures tap different abilities, we test our model for three different measures of reading comprehension: a cloze exercise, a passage and multiple choice based test, and a timed silent sentence reading judgment task. Our findings converge with previous research on the role of vocabulary depth in reading comprehension and also challenge prior work which has compared different reading measures. Implications for theoretical and empirical approaches to understanding reading comprehension, specifically among Spanish-English bilingual students, are discussed.