The paper focuses on the concept of institutions and their relationship with development in developing countries, especially sub-Saharan African countries, in order to understand their specific responses to economic reform and divergent performances vis-à-vis other developing countries. While the concept of institutions has been increasingly used in the literature on economic growth, it has been defined in simplistic or functionalist ways and has lacked explanatory power, with institutions often being reduced to variables in econometric models. The paper aims at refining the concept in order to highlight the limits of the orthodox conceptual framework and the economic reforms usually demanded by the multilateral financial institutions, which did not improve the problematic situation of African states and their integration into the global economy. The first part critically reviews the concept of institutions in the orthodox literature and its uses by the multilateral development agencies. In particular, it shows the limits of the quantitative approaches and the recurrent problems of institutional endogeneity. The second part proposes an alternative theoretical framework. It proposes a new approach of the nature and transformation of institutions, distinguishes different levels of institutions in terms of form and content, which show the lack of relevance and superficial character of the usual typologies (for example, formal-informal), and analyses institutions in terms of their composition with other existing institutions. The third part highlights the limited understanding, in orthodox theories, of the role of politics in the emergence and stabilisation of institutions. It analyses the different dimensions that link the concept of institutions to political economy issues, particularly through the concepts of state credibility, legitimacy, and the developmental state. The final part concludes in examining the effects of globalisation from the point of view of states and institutions in developing countries.