Data on Californians' attitudes toward nuclear power and the nuclear power plants initiative were collected in a two-stage panel survey of a probability sample. Descriptive analyses, analyses of structure, and analyses of evaluations and their determinants were the techniques used. The study found that most survey respondents knew very little about nuclear power plants, but knowledge about nuclear power was almost entirely independent of evaluation of nuclear power. Further, opposition to nuclear power follows primarily from an internally consistent set of beliefs about the general riskiness of nuclear power plants. The belief most highly correlated with evaluation is the individual's assessment of the likelihood that radioactive wastes will harm future generations. Opposition to nuclear power on the part of the average citizen is apparently not part of a strong, well-defined ideology emcompassing other issue positions. There was no evidence of strong links between attitude toward nuclear power and social background.