The pattern of diversification within U.S. manufacturing between 1963 and 1977 are examined. Firms didn't diversify at random; they were more likely to enter rapidly growing industries, and industries that were related to their primary activities through supply relationships or marketing similarities. Research and development (R & D) expenditures also influence the observed patterns. R & D intensive industries generate outbound diversification and attract inbound diversification. However, the strongest influence is directional; R & D intensive firms channel their diversification toward R & D intensive industries. Much diversification reflects the transfer of sharable organization capital among related activities.