This paper explores the role of imports in the internationalization process of US firms. It finds that imports play an important role in this process, particularly in the firm's attempts to learn about foreign opportunities to obtain inputs and to form relationships with foreign firms. This role differs depending on company characteristics such as industry (manufacturing or services), technology intensity, and company age. Imports tend to occur early in the internationalization process, sometimes after exports and other times earlier than exports. Higher-tech firms and service firms tended to import before they entered into exports, while manufacturing firms broadly began their internationalization with exports and imports at about the same time. Older and younger firms did not differ on this criterion. In the early 21st century, imports fit importantly into the supply chain for many if not most firms, generally enabling them to reduce costs through purchase of imports or offshore production/assembly. Service firms, however, tended to view imports as much less important than manufacturing firms, given that service firms cannot import final products for resale or for offshore assembly, but can only acquire inputs into their service provision activities. Service firms faced fewer opportunities to learn from foreign suppliers than manufacturing firms, since they are producing services and generally importing products.