Fossil fuels will probably be our main source of energy in the foreseeable future. The fossil fuel that is currently receiving the most attention is oil sands. A focus of many companies with oil sands operations is to look for more environmentally friendly and still economically feasible methods to produce this resource. This thesis focuses on determining the microbial communities in Alberta’s oil sands and their activities with the intention of eventually utilizing this information for improved production strategies. The microbial communities from oil sands outcrops, mined oil sands and oil sands cores were assessed in detail. Oil sands at different depths had diverse microbial communities, while the subsamples obtained from the same environment also displayed varied populations. All oil sands microbial communities have thermophilic genera with enhanced potential in bitumen biodegradation. The combination of oxygen, high temperatures and the absence of light was shown to greatly stimulate bitumen biodegradation.