Morphological processing is the use of morphological structure during word reading. This study examined the role of morphological processing in automaticity in word reading processes and asked whether automatic morphological processing made a unique contribution to decoding, oral reading fluency, and reading comprehension outcomes of middle school students. In addition, this study asked whether these contributions were moderated by having a word reading difficulty. Seventh- and eighth-grade students (n = 80) participated in the study. Students were divided into two reading ability groups: proficient readers (n = 55) and student with word reading difficulties (n = 25). They completed two remote sessions: a standardized assessment session and an experimental task session. A battery of six standardized measures was administered to assess students' decoding, oral reading fluency, reading comprehension, and oral language abilities. In addition, eight computer-administered experimental tasks (four different tasks, each with a masked and an unmasked version) were used to measure automaticity in reading morphological words (e.g., "eagerness") and nonmorphological words (e.g., "embarrass"). Three analysis approaches were used in a conceptual replication of two previous studies (Roembke et al., 2019, 2021): mixed analyses of variance (ANOVAs), hierarchical regressions, and commonality analyses. Results indicated automaticity in reading nonmorphological words most consistently accounted for unique variance in decoding and oral reading fluency. However, automaticity in reading morphological words was the only independent variable that accounted for unique variance in reading comprehension, and it also accounted for unique variance in oral reading fluency. There was no evidence that the unique contribution of morphological processing to oral reading fluency or reading comprehension was moderated by having a word reading difficulty. These findings suggest that the role of morphological processing in reading may still be developing in middle school 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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]