My early work focused on technical aspects of test development such as standard setting, item bias detection, and validity theory. A cardinal principle of validity research, however, is that test validity depends on how a test is used. As a result, I began to consider contexts of test use. For example, should a readiness test—made up of old IQ test items—be used to keep children out of kindergarten? My most recent work focuses on classroom assessment, especially formative assessment. Drawing on cognitive research and sociocultural theory, I examine ways that assessment can be used as an integral part of instruction to help students learn.