Chapter 5 explores transitivity systems and structures. It concentrates on the evidence used to motivate descriptions of paradigmatic relations. At stake here is the weight given to evidence of different kinds, including arguing from above, around and below. This chapter also foregrounds the cline of delicacy with respect to both system and structure, exploring what happens when general transitivity classes are explored in greater detail and issues that arise with respect to how much subclassification should be reflected in function structure labelling.