Electricity and natural gas markets have traditionally been serviced by one of two market structures. In some markets, electricity and natural gas are sold by a dual-product regulated monopolist, while in other markets, electricity and natural gas are sold by separate single-product regulated monopolies. This paper analyzes the relative pricing and investment decisions of electricity firms operating in the two market structures. The unique relationship between these two products, namely that electricity and natural gas are substitutes in consumption and natural gas is an input into the generation of electricity, allows me to gain inferences regarding the efficacy of regulation in both the electricity and natural gas industries. The results imply that both electricity prices and reliance on natural gas generation are higher in a dual-product setting, both suggestive that regulators respond to the relative incentives of electricity and natural gas firms.