This article describes the development and validation of a scale measuring the interactivity of websites. Three studies were conducted to verify the factor structure, content validity, discriminant validity, and reliability of the scale. Results from the studies showed that interactivity comprises three correlated but distinct dimensions: active control, two-way communication, and synchronicity. The multidimensional scale showed a high level of validity and reliability and yielded consistent ratings among both experienced and inexperienced internet users.