Research, development and human capital accumulation

We develop an endogenous growth model that integrates research and developm ent (R&D) with human capital accumulation. Given decreasing returns to scal e, together with a threshold constraint on human capital, in R&D, steady-st ate growth is determined solely by preferences and human capital technology : it is independent of research activity which, itself, is driven by human capital accumulation. In accordance with recent empirical evidence, the mod el implies that long-run growth is both independent of scale effects and in variant to a wide range of policies.