Single-case data are frequently used in school psychology. In research, single-case designs allow experimenters to provide rigorous demonstrations of treatment effects on a smaller scale and with more precise measurement than traditional group experimental design. In practice, single-case data are used to evaluate the effects of school-based services to make decisions at the individual level within a multitiered system of support (MTSS). School psychology and related fields (e.g., special education) have worked to increase the rigor of single-case data by developing standards for single-case experimental design and developing robust single-case effect size statistics; however, in practice, single-case data are often collected with less experimental rigor and evaluated using visual analysis of a linear graph as opposed to quantitative effect sizes. This is concerning, as an emerging body of literature suggests that simple elements of the graphical display (e.g., ordinate axis scaling, ratio of X to Y axis length) can have a profound impact on effect size judgments made by visual analysts. Currently, there are no standards guiding the construction of linear graphs used to display single-case data. The purpose of this paper is to advance the perspective that our field must develop and adopt standards of linear graph construction or risk inaccurate decisions within a MTSS framework.