This quantitative study examines the Lexile level, estimated volume, and genre of fourth- and fifth-grade texts used in four popular core reading series to analyze the programs' possible effects on instruction and comprehension. The four series include Houghton Mifflin Harcourt's Into Reading, Lucy Calkins' Units of Study for Teaching Reading, Fountas & Pinnell's Classroom Collection, and McGraw Hill's Wonders. Analyzing the whole-group read-aloud texts designed to practice reading comprehension, this study collected the Lexile level, estimated word count, number of texts, and count of literary and informational text from all four programs. Descriptive statistics showed considerable differences between programs, including low mean Lexile levels, programs with seven times fewer words than others, and too little informational text across all programs. These findings align with other scholars' critiques over the last 20 years that there is a lack of vocabulary, not enough volume of text, and not enough informational text. This data is important in understanding the effects of curriculum on comprehension and reading growth as well as the equity of reading opportunities given to students. [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/en-US/products/dissertations/individuals.shtml.]