IT-based assessment has been advancing rapidly, and its growth is set to accelerate with emerging opportunities for automatic data collection as well as increased possibilities of communication and interaction mediated by IT. In this chapter we aim to present an overview of the range of different opportunities for IT to support assessment. We identify and discuss challenges for moving toward a situation where IT-based assessment can serve learners’ needs as well as the broader needs of the educational system for evaluation. We examine theories related to assessment more generally as well as specifically to IT-enabled assessment and review recent research and development. Scenarios for IT-enabled assessments may take many different forms, some of which hold much promise for supporting learning, but there are theoretical, developmental, technical, and human challenges to be overcome. Our vision is for IT-based assessment design to move forward with designers, teachers, and learners working together to design assessments that support twenty-first-century curricula and pedagogy. In this shared endeavor, we expect that data can be collected and represented to enable learners and teachers to identify achievements; collate evidence of those achievements; diagnose needs, both cognitive and affective; and decide on suitable pedagogical approaches for enabling the next steps in learning. We argue that open assessment resources provide a vehicle for enabling the large-scale developments that are needed to support the development of IT-enabled assessment across the broad spectrum of learning. Some of the more complex twenty-first-century skills of collaboration, problem-solving, critical thinking, etc. present particular challenges. We envisage that it may take many years for our vision to be realized. In the medium term, the need is to integrate IT-enabled assessments where appropriate alongside more traditional methods including teacher assessment.