This action research was driven by the researcher's interest in using curriculum-based measurement as an assessment tool and the effects they can have on student growth throughout the school year. The researcher utilized the STAR CBM phoneme segmentation tool quarterly, beginning in the first quarter, as well as the STAR CBM oral reading fluency passages quarterly, beginning in the second quarter. The research was conducted to analyze the effectiveness of using CBM, specifically phoneme segmentation and oral reading fluency, as a progress monitoring tool with 1st Grade students. The researcher is a first grade teacher in her eighth year of teaching first grade, and her seventeenth year of teaching overall. The findings revealed students were able to show student growth and progress through the scores, though the progress made is not enough to justify its significance. Findings also indicated a slight correlation between having a high phoneme segmentation score and having a high oral reading fluency score. This research was conducted to impact future classroom practices as well as school-wide decisions in placing students in reading intervention/Title I services.