The transformations currently underway in agriculture are throwing the spotlight on the studies and methods currently used to design innovative farming systems. This chapter analyses the specificity of five approaches for co-designing technical systems that have been tested in France and in some African and Latin American countries. They are based on a high level of interaction between actors involved in these approaches, and are facilitated by a range of intermediary objects such as modelling tools and agricultural experimentation in a rural environment. They have led to the production of operational and scientific knowledge on technical changes and the conditions under which they can be implemented at the farm level, as well as the institutional conditions conducive to the emergence of new systems. These approaches rely on skills that go beyond those pertaining to agronomy alone; the inclusion of social science researchers may become necessary, in particular to analyse how to hybridize various types of knowledge in order to accompany innovation on farms and in territories.