The attention of Portuguese historians have been polarized around the study of elites and popular groups, paying few attention to sectors of the population that do not fall into these two categories. The main goal of this thesis is to increase knowledge about the composition of the wealth, the houses, and the ways of living and the consumption of the intermediate groups. Throughout the first chapter we examine the use of the expressions "middle state", "middle people", middle, middle class, in Portugal, mainly during the seventeenth and eighteenth centuries, when this vocabulary spread out. With this study, we intend to emphasize, on the one hand, the multiplicity of social representation schemes and taxonomies that coexisted during the period under analysis and, on the other hand, to prove that, despite the legal discourse and normative framework, the notion of middle ranks and the visions of society that include it were widespread in Portugal in the seventeenth and eighteenth centuries. This analysis also seeks to justify our terminological choice. In the second chapter we undertake a discussion of the sociological categories and the model of analysis adopted. We explain why, even considering that in the period and spaces considered the Portuguese society was officially organized into orders and states, we analyse it considering sociological categories that are closer to class than to order or state. Not class in the Marxist sense, but a class that defines itself in a multidimensional space that emphasizes the statute, but also considers the economic aspects. Then we undertake methodological considerations with the analysis of the main historical source used, that is, inventories, highlighting its weaknesses and strengths. The third chapter corresponds to the analysis of the context or, in other words, the geographical, demographic, social, economic and political description of the city of Lisbon, which we chose as the background for the analysis of intermediate groups. In the fourth chapter, we characterize the sample and, in the fifth, we focus on the levels and composition of wealth, and the consumption of the intermediate layers. In the sixth and seventh chapters we launched a multidisciplinary look at houses, at the private interaction space of the intermediate layers, which is first seen as a space of inhabiting and then as a space for consumption. Thus, in the sixth chapter we characterize the habitat of the urban intermediate layers from the point of view of the property regime that linked the families to their houses, its the average value, prevailing typologies, number of floors, areas, number of divisions and functional specialization. In the second part of this chapter, we look at some case studies, trying to integrate the buildings in the city, to know the people who inhabited it, their occupation, how the spaces were used and the conception of life these spaces reveals. In the last chapter we analyse the house as a space for consumption. Focusing on the national reality and starting from the observation of the relation between social position and the possession of objects, we focus on the participation of the intermediate layers of Lisbon in the process of increasing the possession of luxury objects. For this we study the diffusion of luxury objects in the intermediate groups, comparing it with the more and less favoured socioeconomic groups. On the other hand, we follow the lead of the privatization process. We seek to detect the advance of the private sphere in domestic daily life in architectural space and material culture through the analysis of the diffusion of domestic equipment connoted with privatization. This analysis is transversal, spanning several chapters. [ABSTRACT FROM AUTHOR]