I aim to develop a truly general thesis that succeeds in unifying the notion of biological individuality across all corners of the tree of life. I intend to generate a definition which is informed by detailed consideration of the particularities of many different major groups of organisms. I plan to write three papers. In one I want to argue that several popular definitions of the individual (in terms of germ soma separation, bottleneck life cycles or sexual reproduction) ought to be reinterpreted as describing lineage specific mechanisms which are sufficient but not necessary for biological individuality. I argue that the significance of these mechanisms comes from their playing a multiply realisable functional role, common to all biological individuals. In the second I mean to argue in detail that individuals are unified in terms of their shared functional role. I develop an account which makes use of the Price equation to spell out this shared functional role. The idea is that I would understand individuality to be about the degree to which some unit is an exclusive level of selection, where this degree can be established using a multilevel covariance analysis. In the third I try to resolve a tension in the literature between those who argue for a pluralistic or permissive concept of individuality, with others who are pushing for a more unificatory or monistic approach. I will claim that reconciliation can be had by accepting an account of individuality which recognises various phenomena as idiosyncratic solutions to a shared problem, so that both the diversity and the commonality of biological individuals can be accommodated at once.