This study aims to look for a new signal of the demographic transition linked in time to the installation and development of an agro-pastoral lifestyle. Demographic growth has always been a component of models for the spread, during the second half of the sixth millenium BC, of the Linear Pottery Culture (LBK), and the analysis of the space-time distribution of sites appears to confirm the hypothesis. Now a different signal is used here to examine in terms of quantitative trends the strength and rate of supposed growth: household size, measured by house groundplan surface-area. This criterion is particularly suitable because the data for houses are more accurate and manageable on a large scale than the data for the sites themselves. Thus the research issue can be addressed with a representative and uniform sample.While the demographic transition is a phenomenon in itself, its coherence can best be gauged by measuring the time passing (dt) after the start of the process in each locality (time zero: t0). The intention here is to look for intrinsic trends in the strength and rate of the process.Using time-spans of 100 or 50 years, changes in the ground surface-areas of 505 houses (433 for the shorter time-span) from the different regions of LBK Europe show a curve with a sharp increase in the first two centuries of a Neolithic economy, with values falling back over the following one or two centuries. A possible rise occurs again up to 450-500 years after the start of the process, but the evidence for this needs completing. So it seems that the average size of the "family" living under the same roof (household) increases considerably for two centuries after t0 and then decreases, before rising again at roughly dt = 500.This growth and decline is visible at a continental scale, as well as at local (Bylany, Merzbachtal) and subregional scale (Aisne, Meuse/lower Rhine), in the same rate and proportions. The trend thus appears universally valid for the LBK.The local data (Merzbachtal) suggest two correlated phenomena: a population density threshold per village and community fission once this was crossed. Further evidence suggests that the process involved the largest households rather than the