The analysis of the physical changes that have taken place in the organization of markets in the western highlands of Guatemala since the early colonial years graphically reveals the penetration of capitalist features in the peasant marketplace. The open plaza is a reflection of the Indian conceptual system, where the main organizing category is "the people from each township" or ethnic group. The enclosed market, instead, reflects westen capitalist assumptions where the "product" is the main organizing category. Even though gradual changes in the organization of markets have been recorded over the past four centuries, substantial changes have occurred in the last fifty years with the construction of enclosed market-buildings following westem organizational and sanitary guidelines. The study is based on the analysis of ethnohistorical sources, ethnographic accounts, and obseryations.El análisis de los cambios físicos que ha habido en la organización en el Occidente de Guatemala desde la Colonia, revelan una penetración con características capitalistas en el sistema de mercados. La plaza es un reflejo del sistema conceptual indígena donde los grupos étnicos son la categoría organizativa. El mercado cerrado reflejó el mundo occidental donde el producto es la categoría principal.