This paper examines the concept of cohesion in the realm of the species-as-individuals thesis. Firstly, we present one main theoretical role it plays on David Hull's account of individuality: cohesion as a synchronic individuating criterion to individuals. Then, we discuss this role in regard of different senses of “cohesion” present in the literature, such as structural, functional, responsive and integrative cohesion (e.g. Hull, 1980; Wilson & Barker, 2010). The discussion seems to show either that cohesion isn't an attribute of all species or that it is something rather trivial. Facing this dilemma, some philosophers choose to relativize the species-as-individuals thesis, whereas others choose to deny it. But there's a way out. One obvious possibility is to refuse the connection between the individuality thesis and cohesion (Ghiselin, 1987, 1997). This option encounters difficulties, at least if we maintain that individuals are synchronically individuated entities. Another possibility is to re-articulate the concept of cohesion. The fruitfulness of such option will be defended at the core of this paper. In particular, we argue for a more relaxing way of treating “cohesion” based on the diversity of biological individuality. If we pay attention to different concepts of biological individuality, we can note different mechanisms that satisfy the theoretical role described above. The cohesive character of biological individuals is diverse, such that no unique sense of “cohesion” can be prescribed to them. So it`s better to take “cohesion” as a complex concept composed of different variables and subject to variation in degrees.