Since the late 1970s, means-based rent assistance has become the main housing policy instrument to the detriment of building subsidies, whose efficiency was brought into question by the 1977 reform. Means-based rent assistance theoretically improves the targeting of populations for whom housing, which remains the number one household consumption item, is deemed to represent too much of a financial burden. Yet the development of this assistance has gone hand in hand with an increase in the cost of housing for the most disadvantaged tenant households. We seek to evaluate the impact of this on the increase in rents for low-income households. The early-1990s reform of the extension of assistance constitutes a natural experiment whereby the effects of housing benefits can be isolated, since it was applied solely to certain types of households and not others. The growth in the rents paid by the low-income households targeted by the reform can hence be compared with that of the households not affected, and the effects of the reform for the households concerned can be identified. We use data from the INSEE Housing surveys to show that the assistance could well have a lot to do with the increase in rents per square metre for low-income households. The estimates obtained show that 50% to 80% of the housing benefit received by these households has been absorbed by increases in their rents.