This study examined a Canadian post-secondary institution in the period between 2010 and 2014, with a follow-up assessment in 2018 in order to understand its evolution with open educational resources (OER) and open educational practices (OEP). In the first timeline, the study looked at drivers that contributed to the uptake of OER in relation to the type of OER and factors contributing to the diffusion of OER. In the second timeline, the study looked at whether OEPs are being sustained and how they evolved at the institution. Results show that within the institution there are both benefits and tensions to being open, and an institutional approach that considers openness on a case-by-case basis is appropriate. In looking at these two time periods, the study fills a gap in OER research by providing a more longitudinal view of an institutional shift towards initiating and sustaining openness.