Private universities are important actors in higher education, and also play a key role in the sustainability debate. But despite their importance, there a shortage of research on how sustainability is being implemented at private universities. Based on the need to address this gap, this paper investigates the nature and diversity of sustainability-based practices undertaken at private universities. It outlines the ways private universities see and perceive sustainability, and examines by means of a survey involving 10 universities from across all geographical regions which educate over 150.000 students, how these universities incorporate sustainabilityrelated practices, as part of their operations. The results suggest that, unlike their public counterparts, about half of the respondents stated that they do not have projects undertaken to promote sustainability in local communities or in their respective regions. Also, some private universities perceive themselves as leaders in sustainability in higher education, while some are still developing a more robust sustainability profile. The conclusions of the paper are that the special features related to sustainable development teaching and research at private universities need to be better identified, in order to involve them more on sustainability efforts. Also, whereas many of them are highly engaged on improving energy efficiency, reduce greenhouse gas emissions, promote sustainable water usage and promote sustainable landscaping, there is a need for them to also engage in other areas. Finally, private universities should engage on further efforts to increase their sustainability activities, which are beneficial to them in financial terms, as well as in respect of their image and the greening of their operations.