California was among the first states in the US to open its retail electricity market to full competition in one step, on 31 March 1998. Being the country's most populous state as well as a trendsetter in the US, this experiment in utility restructuring is being closely watched by many in North America and elsewhere. This viewpoint provides an overview of the developments since the opening of the restructured California market, focusing on both the positive and negative aspects of the experiment, which are still unfolding.(1)