Previous research about firms’ perceptions on the usefulness of public research has not distinguished between technological innovators and non-innovators. With the exception of openness of search, we find that factors shaping such perceptions differ in both types of firms. Non-innovators need market power and the presence of an R&D department to profit from public knowledge. Innovators need less sheltered environments and lesser R&D effort, though the availability of resources and absorptive capacity is necessary. Using a sample of 1,031 Spanish manufacturing firms, we conclude that practical experience in technological innovation enhances firms’ perceptions on the usefulness of public research, not directly but by enabling certain internal changes, i.e. it produces encounters between corporate choices and public research.