This second report from the Measures of Effective Teaching (MET) project offers ground-breaking descriptive information regarding the use of classroom observation instruments to measure teacher performance. It finds that observation scores have somewhat low reliabilities and are weakly though positively related to value-added measures. Combining multiple observations can enhance reliabilities, and combining observation scores with student evaluations and test-score information can increase their ability to predict future teacher value-added. By highlighting the variability of classroom observation measures, the report makes an important contribution to research and provides a basis for the further development of observation rubrics as evaluation tools. Although the report raises concerns regarding the validity of classroom observation measures, we question the emphasis on validating observations with test-score gains. Observation scores may pick up different aspects of teacher quality than test-based measures, and it is possible that neither type of measure used in isolation captures a teacher’s contribution to all the useful skills students learn. From this standpoint, the authors’ conclusion that multiple measures of teacher effectiveness are needed appears justifiable. Unfortunately, however, the design calls for random assignment of students to teachers in the final year of data collection, but the classroom observations were apparently conducted prior to randomization, missing a valuable opportunity to assess correlations across measures under relatively bias-free conditions.