This paper address factors underlying public opinion regarding offshore wind power based on a survey of residents near a proposed development off Cape Cod, MA, USA. Supporters are found to be younger, better educated, and more likely to own their own home. Opponents are more likely to earn over $200,000/year, and more likely to expect to see the project from their daily routine. The overwhelming majority of the population expects negative impacts from the project; much smaller numbers expect positive effects. When asked which factors most affected their position, the most frequently mentioned was damage to marine life/environmental impacts, followed by electricity rates, aesthetics, and impacts on fishing or boating. When the expectations expressed by our respondents are compared with the findings of the project’s draft Environmental Impact Statement, many of the beliefs upon which opinion are based appear to be factually incorrect. Finally, we tested whether change in the project would affect support. The biggest change was an increase in the level of support, by 47% of the sample, if the project was the first of 300 such projects, in sum having proportionately larger impacts as well as greater benefits. Implications of this research are discussed.