Historically, most efforts to improve public knowledge of science and technology have focused on improvements in K-12 schooling, although post-secondary education and informal education have also been mentioned as important factors. Currently, little empirical data exist to determine how or when to best leverage science and technology education energies and resources. This article examines a range of factors potentially contributing to adult knowledge of science and technology. Results from a telephone survey of 1,018 adult residents in greater Los Angeles, California (United States) showed that adult free-choice learning experiences such as reading books and magazines about science and technology, using the internet, and watching science related documentaries and videos were the strongest predictors of self-reported knowledge of science and technology. Privilege, especially higher income and being male, was also an important factor, as were workplace experiences and childhood experiences outside of school. Although formal schooling was a significant predictor of this knowledge, it explained less variance in knowledge than most other factors. This research provides initial data on which to base discussions about how best to support public education in science and technology. (Contains 5 tables and 2 notes.)