The systemic approach in agricultural research, extension and development (FSR&E) has the concept of "farming systems" one of its core analytical levels. However, the intense changes in rurality showed the limitations present in this concept, allowing for the proposition activity system as better appropriate conceptual basis for more accurate reading of reality and organization of work actions. This extended abstract aims, from literature review, rescue the activity system concept in his original proposal and present some recent contributions for improvement, understanding that may well contribute to its suitability and use in the context of Brazilian FSR&E.