The objective of the report is to analyse the trends and characteristics of the families living in the Province of Trieste in the period 2004-2008. The classification of family units and the statistical elaborations are based on data offered by the Population registers of each municipality. As to allow comparability of the elaborated data regarding familiar structures, the criteria and methods chosen are the same as those employed earlier by the Observatory. For the single family type, we analysed the dimension of the family, the citizenship of its components, the age, the number of children and evolutionary trends. The aspects treated were analysed also on a municipality level.