Commercial development of Alberta’s oil sands deposits has been underway since the 1960s. Their growth has always been guided by a strong provincial energy regulator. The interplay of regulation and development has been well served by the generation of public geoscience at the regulator. The role of public geoscience in regulatory stewardship of the oil sands in the Alberta context from the 1960 to 2010 is examined. This examination focuses on the historical delivery of resource appraisal of the oil sands deposits and geoscience in adjudicative support during gas-over-bitumen regulatory disputes.