In the last years, there has been an increasing interest in relational metaphysics in opposition to the traditional metaphysics of natural sciences: atomism. There are two major motivations for this shift. First, the problems and challenges raised by Emergence, since ontological emergent phenomena cannot be explained by linear combinations of immutable elements, although they can be explained by non-linear transformation of relational parts. Secondly, the contemporary developments in Quantum Physics, since features such as entanglement and the violations of Bell theorem – implying non-locality and non-individuality – show that quantum entities are neither metaphysical "atoms" nor the result of linear combinations. More precisely, this Research Area is devoted: i) to elaborate a positive characterization of emergence in terms of a relational ontology, against any atomistic or holistic perspective; ii) to develop a causal and nomological approach for explaining emergent phenomena; iii) to reformulate the notion of cross-level causation (upwards and downwards causation), proposing a relational-horizontal approach in replacement of the traditional vertical and hierarchical perspective of this kind of causation; and iv) to develop a non-fundamentalist relational-transformative ontology of quantum entities that allows ontological emergence; to explain the phenomena that are being unfold by contemporary Quantum Physics, and to elaborate a non-radical form of structural realism.