Delbes Christiane, Gaymu Joëlle. - The Rise in the Number of Isolated Individuals in France : New Trends in Behaviour ? Following a description of the heterogeneity of the population living in one-person households, an attempt is made to trace the factors which have led to an increase in this population. The respective influence of demographic trends, modifications in marriage patterns and the growing tendency among the non-married towards becoming isolated are emphasized. Up to the age of 55, the role of each these elements varies significantly with age, sex and period ; however, for older individuals, these factors have not changed for 20 years. The demographic factor (especially longer life expectancy) and the growing popularity of livin...