Students with specific learning disabilities (SLD) are educated in general education classrooms. As a result, these students are faced with more challenging instructional curricula. Although some students with SLD perform as well in mathematics as students without disabilities, most perform below state standards despite being provided instructional and testing accommodations. Policy makers have envisioned the implementation of instructional accommodations as a primary means of ensuring an appropriate education (Mcleskey, Hoppey, Williamson & Rentz, 2004; Scalon & Baker, 2012) for students with disabilities in general education classrooms (Mc Guire, Scott, & Shaw, 2006). The researcher implemented a non-experimental ex post facto research design to investigate the research hypothesis to determine the relationship between the five most frequently used accommodations by general education teachers who teach students with SLD and student achievement in Algebra 1. At the beginning of the 2016 – 2017 school year, the collection of data began by emailing the Qualtrics Survey Software (V.23) to 185 general education mathematics teachers in Miami-Dade County Public Schools. Four main instructional accommodation constructs were assessed using a 15-item questionnaire. From the responses to the survey, the five of the most frequently used accommodations were determined. Nine general education Algebra 1 teachers from six high schools across the county who reported using similar accommodations and taught three or more students with SLD in mathematics participated in the study. The researcher and two peer researchers conducted in-class observations on the participants’ fidelity of implementation of accommodations (FOI) using a checklist during the period in which they taught students with SLD. An Algebra I test was used for pre- and post-testing to determine student mathematics achievement. The results of the survey indicated that teachers most frequently provided: (a) sample problems of varying levels, (b) guides or prompts or personal (teacher/peer) assistance, (c) extended access to instructional resources and equipment, (d) provided preferential seating and (e) additional time to complete assignment or class projects. Linear regression analysis revealed a significant positive relationship between teacher FOI of accommodations and student achievement (p < .05).