<p>Standardized measures of achievement and teacher-assigned grades (henceforth grades) are both supposed to be measures of achievement. However, there might be concerns that grades are more subjective than standardized tests. The purpose of this study was to examine the relationship between standardized tests and grades in primary students. We collected data from 218 Grade 1 students and 124 were re-tested in Grade 2. Students completed subtests from the Woodcock-Johnson III Tests of Achievement (henceforth test scores) and grades were collected. Separate factor analyses were conducted on the test scores and grades, both yielding a 3-factor model with separate language, reading, and mathematics domains. We then examined the relationship between test scores and grades across domains, grade-level, genders, and schools. Structural equation models found that test scores explained half of the variance in grades across domains, except Grade 2 language. Bayesian paired t-test found that minimal discrepancies between test scores and grades existed across genders and schools. When a difference did exist, grades tended to be higher than test scores; discrepancies typically occurred in verbal subjects but attenuated by Grade 2; there was a female advantage for grades and male advantage for test scores; and, school differences depended on grade and domain. Understanding the degree of alignment between measures could bolster the use of teacher assessment as a valid index of performance in young children.</p>