The electric industry started as a natural monopoly and was regulated to protect the customers from high prices. Electricity deregulation was expected to reduce prices by introducing competitive markets. Every country or state implementing deregulation has gone through a unique experience. In this paper, the impact of electricity deregulation in the state of California is addressed by first examining historical retail prices, and second by developing a model to estimate the grid marginal costs using historical data. Results show that, although some customers pay lower rates today, the average customer does not pay a lower rate due to deregulation. Moreover, the results of the modeling show that the wholesale prices realized were higher than the marginal cost associated with the grid. Impacts of improved grid management are discussed along with transmission investments, market operator start-up and operation costs, energy and environmental goals, advances in technology on electricity prices, and the impact of deregulation on these factors.