Since the early 1970s, the rate of investment, defined as the ratio between investment and GNP, has decreased in Italy more than in the other industrialised countries. The causes of this disappointing performance may be numerous. The paper points out the investment-limiting effects of the changes in the distribution of income, in the external constraints and in the public debt. Attention has also been paid to the impact of the monetary policy on the accumulation. The information necessary for the research has been gathered by reviewing the literature on each topic. On the whole, the above mentioned variables showed significant effects on the investments. The scale of this impact has altered within the periods examined in the study, i.e. 1970-80, 1980-92, 1992-97.