Prompted by the advent of new standards for increased text complexity in elementary classrooms in the USA, the current integrative review investigates the relationships between the level of text difficulty and elementary students' reading fluency and reading comprehension. After application of content and methodological criteria, a total of 26 research studies were reviewed. Characteristics of the reviewed studies are reported including the different conceptualizations of text, reader, and task interactions. Regarding the relationships between text difficulty and reading fluency and comprehension, for students' reading fluency, on average, increased text difficulty level was related to decreased reading fluency, with a small number of exceptions. For comprehension, on average, text difficulty level was negatively related to reading comprehension, although a few studies found no relationship. Text difficulty was widely conceptualized across studies and included characteristics particular to texts as well as relationships between readers and texts. Implications for theory, policy, curriculum, and instruction are discussed.