The historiography of Brazilian Modern Architecture tends to favor the construction of a fictional coherence; determining groups to which all architects that have worked in that period are attached to. However, a more detailed analysis brings to light the existence of multiple forms of action that do not compete for this fictitious unity. Among them, architects who work primarily for the construction market, which imposes rules, resources, economic relations, that contaminate their modus operandi. This thesis tries to determinate by the analyses of two modern architectural offices – MMMRoberto and Henrique Mindlin Arquitetos Associados - in which ways the market impositions do change the work of these architectural firms, leading them to acquire different design characteristics and organizational methods.