Although proposed nanotechnology applications hold great promise, little is known about the potential associated risks. This lack of clarity on the level of risk associated with nanotechnology has forced people to make decisions about consumption with incomplete information. A national random digit dialing telephone survey (N= 1014) was conducted in the United States to assess knowledge of nanotechnology and perception of risk in August 2006. This investigation looks critically at individuals' responses to questions about the balance of risks and benefits of nanotechnology, both at the outset of the survey and after respondents were given a brief introduction to the potential benefits and risks of the technology. Models were created to characterzise respondents who said they did not know how nanotechnology's risks and benefits balanced in the “preinformation” condition but who, in the postinformation condition, had a different opinion. Respondents who were highly educated, members of the Republican Party, or male were more likely to switch from “don't know” in the preinformation condition to “benefits outweigh risks” in the postinformation condition, whereas respondents who were less educated, members of the Democratic Party, or female were more likely to switch from “don't know” in the preinformation condition to “risks outweigh benefits” in the postinformation condition. This is the first study to our knowledge to develop a significant model of nanotechnology risk perception change, specifically with regard to gender differences. The power of information provision to sway opinions is also supported, highlighting the importance of developing educational efforts targeting vulnerable populations.