The purpose of this article is to provide a rationale for collecting and using curriculum-based measurement (CB) data as well as providing specific guidelines for how to collect CBM data in reading, spelling, and math. Relying on the research conducted on CBM over the past 25 years, we define what CBM is and how it is different from curriculum-based assessment (CBA). We describe in detail how to monitor student growth within an instructional program using CBM data in reading, spelling, and math. Last, we discuss reasons teachers should collect and use CBM data. (Contains 4 tables and 4 figures.)