The study investigated how well report card grades communicate to students and parents that state educational standards are being met, standards that are objectively measured by infrequently administered mandated assessments. Data sources were report card grades and external assessment scores for 2006-09 for Ontario Canada. The information that parents and students received about student performance from report cards and external assessments were similar (r[subscript s] = 0.47) to the r = 0.40-0.60 range previously reported. Teachers assigned higher grades than external assessments warranted, even after a major source of construct irrelevant variance in report card grades (teacher ratings on multiple scales measuring student effort and school commitment) was controlled. The relationship of grades to assessment scores was robust across genders, school district types (Public versus Catholic) and language (English and French). Agreement of assessments was higher for grade 6 than for grade 3 and for Writing than for Reading or Mathematics. Report cards provided information about students' future achievement that was accurate and delivered up to 2 years prior to the administration of external assessments. Seventy to 80% of students who reached the provincial achievement standard on one or both prior report cards were successful on the subsequent external assessment, compared to 30-50% of students who failed to meet the report card standard at least once.