Add to ORKGThis paper extends the Brezis, Krugman and Tsiddon (1993) Ricardian leapfrogging model, allowing for a wider variety of development patterns. In a two-region two-sector economy localized leaming-by-doing causes specialization and uneven development. Technological change reverses the existing development pattern if the new technology locates in the lowwage region. However, in contrast to Brezis et al., the development pattern may also get reinforced if spillovers between the old and the new technology make the leading region a more attractive location. The results are not affected by including capital and extending the model to a two-factor Heckscher-Ohlin framework