Thomas A. Angelo, author with K. Patricia Cross, of Classroom Assessment Techniques, gives this definition of assessment:

Assessment is an ongoing process aimed at understanding and improving student learning. It involves making our expectations explicit and public; setting appropriate criteria and high standards for learning quality; systematically gathering, analyzing, and interpreting evidence to determine how well performance matches those expectations and standards; and using the resulting information to document, explain, and improve performance. When it is imbedded effectively within larger institutional systems, assessment can help us focus our collective attention, examine our assumptions, and create a shared academic culture dedicated to assuring and improving the quality of higher education (AAHE Bulletin, November, 1995)

Alexander Astin, Director of the Higher Education Research Institute at UCLA, gives the following definition in his book Assessment for Excellence: The Philosophy and Practice of Assessment and Evaluation in Higher Education:

I shall consider assessment to include the gathering of information concerning the functioning of students, staff, and institutions of higher education. The information may or may not be in numerical form, but the basic motive for gathering it is to improve the functioning of the institution and its people. I used functioning to refer to the broad social purposes of a college or university: to facilitate student learning and development, to advance the frontiers of knowledge, and to contribute to the community, and the society.