Public perception of nanotechnology may influence the realization of technological advances. Laypeople's (N=375) and experts' (N=46) perception of 20 different nanotechnology applications and three nonnanotechnology applications were examined. The psychometric paradigm was utilized and applications were described in short scenarios. Results showed that laypeople and experts assessed asbestos as much more risky than nanotechnology applications. Analyses of aggregated data suggested that perceived dreadfulness of applications and trust in governmental agencies are important factors in determining perceived risks. Similar results were observed for experts and laypeople, but the latter perceived greater risks than the former. Analyses of individual data showed that trust, perceived benefits, and general attitudes toward technology influenced the perceived risk of laypeople. In the expert sample, confidence in governmental agencies was an important predictor of risks associated with nanotechnology applications. Results suggest that public concerns about nanotechnology would diminish if measures were taken to enhance laypeople's trust in governmental agencies.