The study used reading and math achievement data for grades 4 and 5 in 46 Indiana schools to compare estimates of teacher value added from two student assessments: the criterion-referenced Indiana Statewide Testing for Education Progress Plus (ISTEP+) and a norm-referenced test (NRT) that is widely used in Indiana and other Midwest Region states. The study found a moderate relationship between value-added estimates for a single year based on the ISTEP+ and NRT, with average yearly correlation coefficients of 0.44 to 0.65. Overall, findings indicate variability between the estimates of teacher value added from two different tests administered to the same students in the same years. Although specific sources of the variability in estimates of teacher value added across assessments could not be isolated in this research design, the research literature points to measurement error as an important contributor. The findings suggest that incorporating confidence intervals for value added estimates reduces the likelihood that teachers' performance will be misclassified based on measurement error.