This paper focuses on the dual role of R&D - knowledge generation and the technological-competence-enhancing effect of R&D - and its implication for the endogenous evolution of R&D productivity and the pattern of firm growth. In particular, based on the evolution of firm-specific R&D productivity or technological competence, this paper derives a simple R&D-based model of firm growth capable of explaining Various aspects of firm growth. The model proposes three prototype patterns of firm growth, depending on both firm- and industry-specific characteristics. The former includes firm-specific technological competence-enhancing capability and the initial level of technological knowledge, and the latter includes industry-specific R&D appropriability. Specifically, firms with low technological-competence-enhancing capability tend to follow a convergent growth pattern in which firm growth gradually declines, while firms with high technological-competence-enhancing capability tend to exhibit either a sustained or a vicious growth pattern depending on the initial size of their technological knowledge stock. An empirical analysis of unique data on firm growth and technological capability provides Supportive evidence for the role of technological-competence-enhancing capability in conditioning the pattern of firm growth. (C) 2010 Elsevier B.V. All rights reserved.