We develop a model of optimal pattern of economic development that is
first rooted in physical capital accumulation and then in technical progress. We study
an economy where capital accumulation and innovative activity take place within a two
sector model. The first sector produces a consumption good using physical capital and
non skilled labor. Technological progress in the consumption sector is driven by the
research activity that takes place in the second sector. Research activity which produces
new technologies requires technological capital and skilled labor. New technologies
induce an endogenous increase of the total factor productivity of the consumption
sector. Physical and technological capital are not substitutable while skilled and non
skilled labor may be substitutable. We show that under conditions about the adoption
process of new technologies, the optimal strategy for a developing country consists in
accumulating physical capital first; postponing the importation of technological capital
to the second stage of development. This result is due to a threshold effect from which
new technologies begin to have an impact on the productivity of the consumption