Assessment tools influence incentives to higher education institutions by encouraging them to move towards sustainability. A review of 16 sustainability assessment tools was conducted to examine the recent trends in the issues and methodologies addressed in assessment tools quantitatively and qualitatively. The characteristics of the current approaches as well as problems and obstacles are identified, and implications and suggestions offered for improvements. The sustainability assessment tools reviewed focus mainly on the environmental impacts of university operation and issues related to governance. Aspects of education, research and outreach activities are not well addressed by these tools. As activities for sustainability at higher education institutions increasingly involve inter-/trans-disciplinary cooperation and close collaboration with diverse stakeholders in society, it will be of critical importance to develop and implement concepts and methodologies for conducting comprehensive, long-term and integrated assessment of research, education and outreach on sustainability at higher education institutions.