The results from a year-long study to investigate the technical features of easyCBM mathematics screening measures for first grade are presented. Measures were designed based on the National Council of Teachers of Mathematics Curriculum Focal Point standards, which for Grade 1 include (a) Number and Operations and Algebra, (b) Number and Operations, and (c) Geometry (2006). A sample of 145 students was assessed at the beginning, middle, and end of the school year. Reliability of the measures was adequate, and concurrent and predictive validity results--with the TerraNova 3--were moderate. Receiver operating curve analyses, based on mathematics difficulty below the 25th and 40th percentile, indicated adequate classification accuracy. We examine results from the study in the context of linking assessment to instructional decision making. (Contains 1 figure, 5 tables, and 1 note.)