Until recently much of the philosophy of biology had assumed a neo-Darwinian picture of evolution, specifically, one that embraced a paradigmatic biological hierarchy in which genes are parts of organisms, organisms are individuals, and species are sets of individuals. However, current work in biology has challenged this dominant picture on many fronts, showing places where it fails to be isomorphic with significant insights and developments in the current biological literature. The primary aim of this project is to develop a concept of biological individuality in the philosophy of biology that is informed by current research in biology. My account of biological individuality departs from previous philosophical accounts insofar as I see the concept of biological individuality as emerging from a particular type of conceptual framework: one that serves to unite the collection of diverse and disparate research approaches in an integrative research perspective. Consequently, a substantial portion of my project will involve (a) integrating a set of broad theoretical issues in a unifying framework and (b) carefully considering how empirical research projects in different areas of biology, in particular ones that focus on different levels of organization, can alter (or support) this type of conceptual framework. I will argue that from this type of conceptual framework will emerge a concept of biological individuality that offers a higher degree of plausibility and a more ubiquitous application in the biological arena than former attempts. I tease out a concept of individuality by exploring the mereological relationships distinctive to biological individuals.