The dissertation examines conditions under which gas-to-liquids (GTL) technology penetration shifts the crude oil-natural gas price ratio. Empirical research finds long-run relationships between crude oil and natural gas prices. Some studies include time trends that steadily evolve the pricing relationship, while others show a long-run relationship that occasionally shifts significantly. A common hypothesis is that technologies that increase substitutability or complementarity between fuels are the source of the price linkage. However, empirically measuring the effects of a gradually-penetrating technology across narrow time frames is not possible due to intervening economic shocks. This thesis examines the effects of an energy conversion technology penetration on the crude oil-natural gas price ratio through its influence on sectoral energy use in the U.S. GTL must be less expensive and more efficient, and natural gas prices must be lower, than currently forecast for an effect to be measured. In the absence of a technology that explicitly allows for substitution between natural gas and petroleum-based fuels, different rates of demand growth result in a steadily-rising oil-gas price ratio. If a viable GTL technology successfully competes against petroleum-derived refined fuels, it dampens crude oil price increases and brings the oil-gas price ratio below the levels found in cases without a viable GTL technology.