This purpose of this study was to develop a clearer understanding of the complex, interrelated factors that lead to successful informational text comprehension and to determine if or how these factors vary for higher and lower comprehenders. Participants (N = 177) were in grades three through five and were predominately African American (61%) and female (51%). Hierarchical linear regressions were used to investigate how decoding efficiency, vocabulary knowledge, prior knowledge, and intrinsic motivation influenced informational text comprehension. For the whole sample, the complete model with all predictors explained 62.5% of the variance in informational text comprehension. Each reading component explained unique variance, with vocabulary knowledge explaining the most variance. For lower comprehenders, decoding efficiency accounted for a significant amount of variance in reading comprehension beyond age and grade, but was not a significant predictor when all variables were included in the model. For higher comprehenders, vocabulary was a consistent predictor of informational text comprehension. The results reveal the importance of investigating informational text comprehension for different groups of readers and the value of multiple factors, especially vocabulary knowledge, for success with informational texts. [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.]