Responses from the Yale University survey of 650 research and development executives were linked to U.S. trade statistics at the four-digit SIC level for the years 1965-85 to test several hypotheses concerning intra-industry trade. A new index of intra-industry trade was developed to capture both the level and balance dimensions of import and export flows. Intra-industry trade is found to be more extensive, the higher industry R&D/sales ratios were, the more important economies of learning-by-doing were, and greater the relevance of academic engineering research was, and the more niche-filling strategies were emphasized in new product development. When firms oriented their R&D efforts toward meeting the specialized demands of individual customers, intra-industry trade was lower. The highest levels of intra-industry trade were found in loosely oligopolistic industries.