This study investigated the effects of teacher background variables on fourth grade reading achievement data collected from the 2007, 2009, 2011, and 2013 National Assessment of Educational Progress (NAEP) using a causal-comparative research design. Teacher quality variables related to teacher credentials, instructional methods, training, and support were selected from the NAEP background questionnaire. Descriptive and inferential statistical analyses were used to examine teacher background information and fourth grade reading NAEP scaled scores using measures of central tendency, independent t-tests, analysis of variance, and Tukey’s HSD post hoc analysis. Findings suggest that certain teacher quality variables positively impact fourth grade reading achievement. Significant differences existed among fourth grade reading scaled scores for the following variables: teaching credentials [region (p < .05), traditional preparation route (p < .001), highest degree earned(p < .05), years of experience (p < .001)]; instructional methods [reading aloud by students (p < .01), questioning character motives (p < .01), student selection of reading materials (p < .001), explaining/supporting text (p < .05), identifying main theme (p < .001), time spent on reading (p < .001), primary language arts integration (p < .05)]; teacher support [instructional grade level support/technical assistance by reading specialist (p < .05) and mentoring (p < .05)]. This study expands the current literature on teacher quality by exploring the effects of teacher variables on reading achievement.