This chapter provides a brief overview of the available theoretical explanations on determinants of national technological performance and comment on their explanatory power, that is their apparent ability of interpreting existing reality. The transaction specific approach towards national technological build-up and its determinants represents apparently the main stream of the relevant discussion so far. Obviously, it has evolved over time and became more and more refined. Its main methodological assumptions, however, remained basically unchanged. The essence of the institutional approach lies in associating national technological performance with the characteristic features of national economic organization. It is claimed, explicitly or implicitly, that to understand varying national performance in technological build-up, systemic variables must come to the forefront of the analysis. The essential feature of the historical approach is the interpretation of national technological performance in terms of the variables pertinent to the time and place for which the analysis is carried out.